Domestic Scale Aquaponics

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Domest ic Scale Aquaponics: The Form, Function, and Ec onomic Viability thereof Ravi Banerjee New College of Florida Environmental Studies 4/14/2009 Dr. Alfred Beulig New College of Florida

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Acknowledgements Al Beul ig Joel Beaver Ned Poulos-Boggis Meg Lowman Leo Demski iii

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Table of contents Ti tle Page i Acknowledgements ii Contents iii Table of Figures iv List of Tables ix Abstract x Introduction 1 Methods 100 Results 127 Discussion 145 Conclusions 157 Appendix A 158 Appendix B 159 References 165 iii

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Table of figures Figure 1 Co-current foam fractionator schematics 25 Figure 2 Basic granular media filter schematic 26 Figure 3 Powered return biofilter schematic 27 Figure 4 Redclaw crayfish 32 Figure 5 Rainbow Trout 34 Figure 6 Tilapia 36 Figure 7 Channel catfish 38 Figure 8 Mosquitofish 39 Figure 9 Early water culture system de s ign featuring raised, large, grow beds and deep nutrient troughs 66 Figure 10 Simple pump-fed, gravity-retu rn ebb & flow system, utilizing the pump feed as a siphon return for t he ebb cycle and the overflow tube to maintain nutrient depth during the flow cycle 70 Figure 11 Basic raft culture schematic u tilizing relatively static nutrient solution containment 71 Figure 12 Commercial raft culture raceway layout 72 Figure 13 Commercial raft culture raceway with foam board grow beds installed 72 Figure 14 Commercial raft culture system in use 72 iv

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Figure 15 Aeroponic grow system featuring a sealead root chamber and multi direction nutrient solution fogging 73 Figure 16 Floor plan of early nutri ent film techni que research system 75 Figure 17 Flat Polyethylene nutrient fi lm techni que troughing material and preparation schematic 76 Figure 18 Tented nutrient film techni que troughs constructed of sheet polyethylene and utilizing pelletized grow medium. 77 Figure 19 Solid PVC nutrient film technique trough 78 Figure 20 Early stand alone, vertically oriented, cascade style NFT system 80 Figure 21 Cascade NFT system researc hed for use i n low profile vegetable production 81 Figure 22 Lettuce 84 Figure 23 Arugula 86 Figure 24 Collards 87 Figure 25 Basil 88 Figure 26 Dill 89 Figure 27 Chives 91 Figure 28 Watercress 92 Figure 29 Mint 93 Figure 30 Warner Daniels' NFT trough grow system featuring gravity assisted parti culate removal and grow bed dr aining constructed from primarily recycled components 107 v

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Figure 31 Locally captured Channel catfish utilized in the research system 113 Figure 32 Locally captured Blue tilapia utilized in the trial system 114 Figure 33 Population of lo call y captured Mosquitofi sh populating the test system 115 Figure 34 Sawhorse bracket with legs and 48" cross p iece inserted, situated in research location, secured with deck screws 120 Figure 35 The base of the A-fram with the cross-members installed and 2x4" shel ves installed 121 Figure 36 4" water return trough inst alled on 2x4"shelf capped with a full si zed 4" end cap 122 Figure 37 4" water return trough featuring 1" water return port 123 Figure 38 Completed a-frame during in stallation of v ertical NFT grow channels into 4"water return trough and along the upper beam of the aframe. Also depicted is the layout of the microgreen grow area situated internally on the a-frame 124 Figure 39 Fish grow out tanks, situ ated beneath the mi crogreen grow section of the system, connected with and auto siphon made with excess pvc from construction 124 Figure 40 Assembled and installed pump and filter bag components ins talled in system 125 Figure 41 Assembled water distribution inlet 126 vi

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Figure 42 Upper beam of grow frame featuring installed PVC distribution pipe retainer 127 Figure 43 Water distribution pipe installed and co nnected to water pump with vinyl tubing 128 Figure 44 Arrangement of grow bed nu t rient solution distribution tubes emanating from primary water distribution pipe 128 Figure 45 Nutrient solution distributi on tubes posi tioned to supply grow zones 129 Figure 46 Assembled grow system with exterior lighting installed and angled to ev enly distribute light over exterior grow zones 130 Figure 47 Installed and connected electri cal distribution and timing system for grow system 131 Figure 48 Installed and prepared micr ogreen grow contai ners situated in the interior of the a-frame 132 Figure 49 Foam insulation strip, drilled and prepared for installation in system an d insertion of net grow pots 133 Figure 50 Prepared net pot and Rockw ool cube prior to assembly 134 Figure 51 Assembled Net pot and Rockwool cube, ready for insertion into system 134 Figure 52 Assembled net pot and ro ckwool cube, inserted into the insulation board grow bed of a cha nnel within the NFT portion of the system 135 vii

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Figure 53 Seeded NFT grow beds, first planting 143 Figure 54 Seeded Microgreen Grow area, first planting 1 Figure 55 Sprouting Basil, NFT grow zone, first planting 145 Figure 56 Sprouting Spinach, NFT grow zone, first planting 145 Figure 57 Sprouting Bibb lettuce, NFT grow zone, first planting 146 Figure 58 Sprouting Mint, NFT grow zone, first planting 146 Figure 59 Radish and Mustard Micr o green bed prior to fi rst harvest 147 Figure 60 Mesclun and Mustard microgr een grow beds pri or to first harvest 148 Figure 61 Sprouted Basil and Bibb lettuce NFT grow troughs 148 Figure 62 Bibb lettuce grow trough, showing many sprouts prior to thinning 149 Figure 63 Sprouted NFT grow troughs 149 Figure 64 Microgreen grow beds prior to second har vest from first planting 151 Figure 65 Radish microgreen grow bed ready for second harv est from first planting 152 Figure 66 Mesclun grow bed ready for second harv est from first planting 153 Figure 67 NFT grow bed, sprouted, second planting 156 Figure 68 individual microgreen grow be d, planted with radish, ready for harvest 157 Figure 69 Volume comparison of harvested radish microgreens from a si ngle grow bed against a six-inch ruler 157 viii

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List of tables Table 1: Dissolved Oxygen (mg 0, per Liter, ppm) at Saturation in Freshwater. Brackish Water, and Se awater at Different Temperatures 18 Table 2: Percentage of Free Ammonia (as NH3) in Freshwater at Varying pH and Water Temperature 21 Table 3: Redclaw crayfish enviro nmental survival requirements 32 Table 4: Rainbow trout environmental survival requirements 34 Table 5: Tilapia environmental survival requirements 35 Table 6: Channel catfish environmental survival requirements 36 Table 7: Mosquitofish environmental survival requirements 38 Table 8: Plants tested in system 94 Table 9: Assessed market va lue for vegetative produce 113 ix

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Abstract Aquaponics is the integrated production of plants and marine organisms in closed recirculating sy stems. The integration of fish and vegetable growth systems creates a more efficient production environment. Aquaponics systems offer numerous economic benefits stemming from many sources includin g nutrient reuse, decreased space and water usage, and a reduction in combined infrastructural costs. Aquaponic farming methods have b een in existence for thousands of years. However, as societ ies develop, the benefits o ffered by this field of agricultural science become more a pplicable. Aquaponics is a viable means of enabling not only commerc ial farmers to increase their production but for the individual to supplement or entirely supply their domestic produce needs. For decades the equipment required to manage a successful aquaponic syst em has been unavailable to the average consumer, however, with mo dern technological and scientific advances, has become possible and productive for the individual to produce food within the confines of their own home in an economically beneficial manner. This thes is examines and tests methods of small scale aquaponic system operation and design. x

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xi Introduction Aquaponic technology, which ca n be dated back thousands of years, is rapidly increasing in applie d value in our 20th century world. Within the currently expanding and increasingly aggressive global economic environment, the worldwide ag riculture industry is faced with continually growing demand for th eir products, all the while being challenged with ever-increasing cost s of doing business, costs which are passed on to the consumer. The agriculture industry will have to evolve in order to produce their products on a higher level of production in order to survive, prosper, and provide. Histor ically, improvements in agricultural methods have been based on improvements in methods of monoculture production. However, instead of si mply developing more intensive methods of monoculture, combinations of aggressive monoculture farming methods into polyculture production methods may enable greater yields at a lower cost. This approach to increased pr oduction by combining multiple agriculture methods dates back thousand s of years. The earliest written

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records of th is innovation in agri culture are from ancient China c. 2600 BCE (Nelson, 1997). The first systems were developed as a means of increasing food production on small farms with limited resources. They have since evolved from such very rudimentary attempts at increased output to very complex integrated agri-aquaculture systems with vast commercial production capability. The polyculture approach to increased agricultural production does not negate the need for contin ued improvements in monoculture production but instead is a meshing of two vital evolutions of agricultural science. The advancement in the field of controlled cultivation of aquatic animals, or aquaculture, has, over a long period of development, made possible the production of great quantities of food from relatively small enclosures of water (Timmons, et al., 2002). Over the same period of time horticultural improvements have led to the development of confined soilless cropping methods, known today as hydroponics, capable of producing far more produce per area and time than previous methods The origins of modern hydroponics and aquaculture dates back thousands of years. Among the most popularly cited examples of early hydroponic systems are the Hanging Gardens of Babylon from 600bc (Nelson, 1997). Evidence of the early existence of hydroponics remains in the form of hieroglyphs along the Nile; which depict the growing of plants 2

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in water witho ut soil, dating back seve ral hundred years BC (Nelson, 1997). Similar forms of farming existed in other areas of the world well before contact between civilizations was know n to have occurred. The Floating Gardens of the Aztecs can best be de scribed as hydroponic raft culture (Nelson, 1997). These gardens were created first in the 11th century, and still exist in some areas exist to this day. A century later, Marco Polo described similar floating ga rdens in China in his travel logs (Nelson, 1997). Aquaponics may have begun with people taking advantage of naturally occurring incidences of enclosure. One of the most notable early examples of aquaponic culture occurred in ancient China (Nelson, 1997), where rice paddies were sto cked with fish and other aquatic animals. This may have first occurred accidentally as the paddies were flooded, and indigenous species were tr apped. However, such incidental captures were soon realized as a b enefit by farmers and would naturally become encouraged to the point of intentional and selective introduction of animals by farmer s (Rabanal, 1998). As methods of monoculture improved the improvem ents were also soon adapted and incorporated into integrated agricult ure systems, one field of which is aquaponics. Such improvements in monoculture technology benefited not only commercial agricultural institutions, but provided benefit to domestic 3

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producers as well. Many technolo gical improvements originating in commercial farming operations provided great benefit to the home grower. Worldwide, millions of people are reliant on self produced foods. Even in developed countries many people supplement their dietary intake with domestically produced foods. Outside of necessity, many people choose to grow their own foods as a fo rm of recreation, in order to ensure freshness, as a means to eliminate market dependency, and as a method of saving money. As integrated agri culture component technologies have developed, the opportunities presented by the advances have become available for the domestic food producer. The system components, however, have frequently been out of the effective price range and useful size constraints for the domestic grower. However, the benefits of such integrated agricultural systems on the domestic scale are significant. A domestic grower implementing such technological and methodological improvements co uld benefit through increased production, reduced space usage, or both. Commonly a problem faced only by developing nations, adequate dietary needs of vegetables are not being met on a global scale, affecting wealthy and impoverished coun tries alike. In t he United States people are eating fewer than the recommended number of servings of vegetables every day. One possible caus e for this is the rapid increase in price of consumer produce. No other portion of the food market has 4

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increased in cost to the Amer ican consumer as rapidly. The price of produce has risen, on average, over 118% since 1985 (Putnam, et al., 2005). Even with price increases, Americans spent over $17 Billio on vegetables in 1999 (ACNielsen Homesc an data, 2000), and still did not consume, on average, their recommend ed daily servings of vegetables (Blisard, et al., 2007). With the av erage American spending only about $5.02 per week (Blisard, et al., 2007) on fresh pr oduce it is easily understandable to the market expe rienced consumer, that individuals may be falling behind on their intake of vegetables. This trend may also be due in part to the common diffic ulties faced in maintaining fresh produce in supply in the home without waste. Most fresh produce has an extremely short shelf life and therefore consumers may be opting for other selections which are less likely to spoil. The average American consumer may be willing to increase thei r daily vegetable intake to the recommended daily level, if, instea d of spending what they would on vegetables in the store, invest in a vegetable production system for their home, which could conceivably pr oduce more than the minimum recommended quantity of produce at a lower cost. The average American household in 2004 consisted of 2.6 persons (U.S. Census Bureau, 2004). Therefore the weekly average cost s of such a system would have to be below $13.05. If the operating costs were to be equal to this figure, then there would never be a break-even point at which the system had 5

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sav ed the user any money, and the only values the system would provide would be a form of recreation. I will attempt to design, construct, and operate such an integrated agricultural system on a scale suitable for the American home and at a cost which would be rendered negligible within a year based on the value of the foods produced for the operator. 6

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Origins of Aquaculture Fish culture Early beginnings There are a number of theories re garding the origins of aquaculture. Many of these theories may be co rrect and may have occurred during similar periods, but are applicable in geographically distinct areas. There are four largely accepted theories pertaining to the origins of aquaculture. Fish are a vital source of protein for many of the worlds people. As human populations grow, wild harvests of fish increase as well. In many areas the harvests have grown so large that co llection from the wild is no longer sustainable and population levels are rapidly declining as prices for the species demanded rises. Fish cult ure has been practiced by numerous societies for many centuries. As the cost of producing fish from the wild increases, commercial farming of fish has become more widespread and profitable. From centuries-old beginnings, fish culture has become a staple method of supplying fish for many markets. The Oxbow Theory 7

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The Oxbow theory of aquacultur e primarily pertains to inland riverine areas. Naturally, over time, rivers meander back and forth across the land, at times developing curves called oxbows. As the rivers path wanders across the landscape these oxbows occasionally become isolated from the rivers main flow, forming lakes teeming with the creatures which would naturally inhabit the river. Human po pulations living along the banks of these rivers were by nature, commonly involved in harvesting from them and would have undoubtedly discovered the landlocked oxbows to cont ain fish which could be harvested as well. Over time the local human populations ma y have depleted the harvestable populations of fish in the oxbows, they may have realized as well that seasonal flooding could replenish the supply of fish residing within them. Enterprising peoples may have even improved on such natural cycles by enclosing their own oxbow areas or mo difying existing ones. These people may have then negated their reliance on flooding for the restocking of the oxbows, instead stocking them themselves, thereby beginning the aquacultural management of the oxbo ws. This system would slowly have been improved upon until complete aquacultural management was attained. Bangladesh with its extensiv e river systems and distinct rainy and dry periods is an area well suited for aquacultural development by this theory. (Rabanal, 1998) Catch and Hold Theory 8

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Throughout the ages water has played a critical role in the placement and development of civilizations. It also was common practice to construct aquatic areas in and around civilizations to serve as sources of water, recreation, sanitati on, and means of defense, such as the wet moats of European lowlands. Such waters were not initially intended for the culturing of fish, but, to sate the demands of rulers for recreation or perhaps as a defensive larder, they were stocked with fish. Of the fish stocked in these ponds, some species were more readily able to live and populate while others di ed in containment. With experience, species more easily sustained in su ch systems would become the primary species stocked into newer systems. This then would have been developed into a more progressive sy stem, with a greater focus on food production, through the feeding of the captive fish to produce a greater yield. (Rabanal, 1998) Concentration Theory Many tropical areas of the world experience monsoons or other seasonal weather events; one bringing a period of strong rains, the other bringing little or no precipitation. Commonly the rainy seasons produced such precipitation that the waterw ays became swollen and geographic lowlands were flooded. These seas onal marshlands were rich in vegetation and aquatic organisms, including fish, providing exceptional 9

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hab itat for organism growth and reproduction during the wet season of the year. As the rainy season recede d into the dry season, the water in these flooded lands gradually recede d as well, draining the flooded plains, leaving only topographically deep areas and the rivers with water. This reduction of available aquatic space resulted in the fish of the flooded region relocating and therein concentrating themselves in these remaining areas of water. The surrounding communities would naturally have found these areas to be excell ent fishing grounds after the water had receded. In the beginning, most of the fish in these concentrated areas were likely caught without regard to size or maintenance of population levels. Possibly, as the communities develope d, the immature fish were left in, returned to the water, or gathered and transferred to other confined water areas where they would be allowed to grow-out to a more productive size. (Rabanal, 1998) Trap and Crop Theory The Trap and Crop theory is most pertinent to coastal areas with their characteristic tidal influences and commonly brackish waters. The prime coastal areas for these theories to have developed were those which abounded with lagoons, cove s, and enclosed swamps, which were periodically flooded and drained. The local peoples of such areas long ago realized that these spots in whic h fish, at times of low water were 10

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unable to ex it, or, through changes in the land such as mangrove growth, became permanently confined, served as rich sources of edible bounty. The regular influx of fish in some of these areas led the peoples of the area to improve on natural processes. Humans began to develop methods of trapping which would allow fish to enter these enclosed pens while precluding them from exiting. Howe ver, as this method would become more widely utilized in an area, it would result in a decrease in the local population size. These enclosed areas also allowed the community to hold their captured fish for a period of ti me, and instead of immediately killing the fish caught for personal use or profit, the fishermen began to leave the fish in the enclosure until they grew to a larger size, providing greater return, thus starting a primitive fo rm of aquaculture. Later, true aquaculture management was developed through the construction of dikes or permanent containment for fish and stocking additional finfish or crustaceans to supplement the cont ained populations. (Rabanal, 1998) Containment Methods of organism containment ar e extremely varied. This thesis, being restricted to system designs of such a size as is suitable for a domestic residence, eliminates pond cu lture, the culture of fish in earthen containment system, due to its gener al size, as a viable means of Aquaponics. In addition cage culture, commonly practiced in large 11

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bod ies of water cannot be considered as viable. Therefore, discussion of containment systems will be limited to recirculating tank culture systems which minimize water use. The primary focus of tank cult ure is the design of the fish containment tank itself. Decisions on tank design must incorporate numerous factors such as maximization of stocking density and ease of system maintenance. In terms of ma ximized fish production and waste removal, circular tanks offer many advantages. These advantages include uniformity of the culture envi ronment while maintaining a variable range of rotational water veloci ties and improved speed in the concentration and removal of settlable solids, both of which optimize fish health and condition. Circular tanks are simple to maintain, and provide uniform water quality. Recommended di ameter to depth ratios vary from 5:1 to 10:1, although some systems us e tanks with a ratio as small as 3:1 (Timmons, et al., 2002). The choice in diameter to depth ratio is influenced by available floor space, fish stocking density, culture species, and feeding levels. In circular tanks tank water velocity is essential in the tanks ability to self clean. The water velo city maintained in the tank should be as uniform as possible and as swift as necessary to ensure self-cleaning of the tank. However, water velocity should not un duly strain the culture species. 12

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Opti mal velocities are in the range of .5 to 2 times fish body length per second (Timmons, et al., 2002). Water The most fundamental element of aquaculture is, naturally, water. In order to ensure a stable system, the water it contai ns is the most commonly modified and closely monitored component. Through close control of the culture environment, the water, it is possible to operate a nearly closed aquaculture system in which minimal water exchange is required. In addition, in closed reci rculating aquaculture systems, it is more easily possible to optimize fish health and growth rates through close system control. Although there are ma ny naturally variable parameters in the aquatic environment only a small number of these are crucial to fish health. The most important of these are temperature, suspended solids, pH, and the concentrations of dissolved oxygen, nitrite, ammonia, CO2, and alkalinity. Although independently important, the interactions these parameters have with one another have the greatest influence on fish health (Timmons, et al., 2002). The above noted water quality parameters interact with each other in both positive and negative ways. Fo r example, aeration difficulties will lead to decreased dissolved oxygen levels; enabling CO2 levels to increase. However the exact relationsh ip between water quality and fish 13

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growth rates i s complicated. For exam ple, the majority of fish lack the ability to control their body temper atures and therefore their internal temperature is dependent on that of the surrounding water. As the temperature of the water changes it is able to carry different levels of dissolved gasses, at the same time chan ging the metabolic rate of the fish residing in it (Timmons, et al., 2002). When the water temperature is lower, the fish have lower metabolic rates and therefore produce fewer waste products. As the water temperature in crease the reverse occurs and the fishs metabolic rates increase and the levels of waste produced and elements consumed increase as well The changes in production and consumption of these elements and ha ve a severely negative effect on the system if allowed to slip beyond acceptable normal, levels, and may result in increased fish stress (Timmons, et al., 2002). Water Quality Dissolved Oxygen Out of every dissolved gas in the water contained by an aquaponic system, dissolved oxygen is the most crit ical. It is ironic that due to the chemical properties of water, the highest concentrations of dissolved oxygen possible, most ideal for fish occur at low water temperatures, incompatible with most fish. The air we breathe consists of approximately 21% oxygen; water is not capable of sustaining such levels. 14

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Table 1: Dissolved Oxygen (mg 0, per Liter, ppm) at Saturation in Freshwater. Brackish Water, and Se awater at Different Temperatures Temperature(C) 0 4 Chlorinity (0/00)18 12 16 20 1 14.24 13.54 12.91 12.29 11.70 11.15 2 13.84 13.18 12.56 11.98 11.40 10.86 3 13.45 12.84 12.25 11.68 11.12 10.59 4 13.09 12.51 11.93 11.38 10.83 10.34 5 12.75 12.18 11.63 11.09 10.57 10.10 6 12.44 11.86 11.33 10.82 10.32 9.86 7 12.13 11.58 11.06 10.56 10.07 9.63 8 11.85 11.29 10.80 10.32 9.84 9.40 9 11.56 11.02 10.54 10.07 9.61 9.20 10 11.29 10.77 10.30 9.84 9.40 9.00 11 11.05 10.53 10.07 9.63 9.20 8.80 12 10.80 10.29 9.84 9.41 9.00 8.61 13 10.56 10.07 9.63 9.21 8.81 8.42 14 10.33 9.86 9.41 9.01 8.62 8.25 15 10.10 9.64 9.23 8.83 8.44 8.09 16 9.89 9.44 9.03 8.64 8.28 7.94 17 9.67 9.26 8.85 8.47 8.11 7.78 18 9.47 9.07 8.67 8.31 7.97 7.64 19 9.28 8.88 8.50 8.15 7.08 7.49 20 9.11 8.70 8.32 7.99 7.66 7.36 21 8.93 8.54 8.17 7.84 7.52 7.23 22 8.75 8.38 8.02 7.69 7.39 7.11 23 8.60 8.22 7.87 7.55 7.26 6.99 24 8.44 8.07 7.72 7.42 7.13 6.86 25 8.27 7.92 7.58 7.29 7.01 6.75 26 8.12 7.78 7.45 7.16 6.89 6.63 27 7.98 7.64 7.32 7.03 6.78 6.52 28 7.84 7.51 7.19 6.92 6.66 6.40 29 7.69 7.38 7.08 6.82 6.55 6.29 30 7.56 7.25 6.96 6.70 6.45 6.19 'Conversion Chlorinity (CI) to Salinity (S) is: S = 1.80655 x CI Normal seawater is 35 0/00 or 35 ppt S (19.37 ppt CI) (Timmons, et al., 2002) It is difficult to specify critical dissolved oxygen concentrations for fish because the effects are influenced by other factors such as exposure time, fish health and size, temperature, CO2 levels, and other factors. Under normal conditions, optimal fish health requires oxygen levels of about 5 mg/L. (Timmons, et al., 2002) 15

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Fortunately, increasing dissolved oxygen concentrations in an aquaculture system is extremely easy. Forced aeration of an aquaculture system can be achieved in many wa ys. One simple method is to allow water returning to the tank from the fi ltration system to freefall into the tank, increasing the surface area of water exposed to the atmosphere. Another similar method is to forcibly spray the returning water into the primary tank, which will create greater numbers of air bubbles of a finer size, therein increasing the surface area of water exposed to the atmosphere. A third method involves th e injection of air into the water of the system through gas pumps, the forc ed air is then expelled into the tank through a mechanical diffuser which emits small bubbles, increasing the surface area of the water exposed to the air. Temperature The second most crucial component to water quality in an aquaponic system is water temperatur e. Temperature controls much of a fishes life, and alters ma ny components in the water in which the fish lives. It has a direct affect on the fishes physiological processes such a respiration rates, feeding and assimilation levels, growth, reproduction, and other behaviors (Timmons, et al., 2002). Temperature is so critical to fish that cultured species are commonly grouped by temperature preferences, being classifi ed as cold-water, cool -water, and warm-water 16

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fishes. The cold water species prefer water temperatures in the range of 50-60 OF, cool water species preferring 60-68 OF, and warm water species preferring temperatures ranging above 68 OF (Timmons, et al., 2002). These are, however, generalizations, ea ch species has its own optimum temperature range which maximizes growth and upper and lower limits beyond which they cannot survive. While it may seem optimum to contain fish at the upper spectrum of their livable temperature range due to increased metabolic rates and therefore possible increased growth rates, it is in fact counterproductive. As their metabolic rates increase with temperature, dissolved oxygen levels decrease and the fish must expend more energy to respire and process foods, therein the law of diminishing returns makes it less productive than maintaining the fish at a lower temperature (Timmons, et al., 2002). Temperature can be controlled in an aquaponic system through the use of chillers and heaters. However, these systems are expensive to install and require great deals of electricity to operate. Depending on the system it may prove more economical to simply select species more aptly suited for the temperatures natural to the system. Ammonia / Nitrite / Nitrate 17

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Ammonia, nitrite, and nitrate are all derived from nitrogen and are considered contaminants in aquacult ure systems. While a considered a system contaminant, nitrogen is an essential element for all living organisms. It is required, however, in relatively small quantities by the culture species, requirements which are easily satisfied. All excess nitrogen is therefore a waste product that must be removed. The majority of fish waste is nitrogenous; it is expelled through gill diffusion, gill cation exchange, as well as urine and fecal excretion. In addition to this, nitrogenous wastes within the system are also produced from the decay of organic debris such as dead fish uneaten feed, and nitrogen gas in the atmosphere (Timmons, et al., 2002). Ammonia, nitrites, and to a certain extent, nitrates, are highly toxic to fi sh and therefore the decomposition of these nitrogenous wastes is vital to most aquaculture systems. The compounds ammonia, nitrite, and nitrate are all soluble in water. Ammonia exists in two forms, Ionized and un-ionized, NH4+ and NH3 respectively. The sum of the two is called total ammonia. Un-ionized ammonia is the more toxic of the two forms and exists as NH3-N. Changes in temperature, pH, or salinity result in modifications to the proportion of ionised to iodised ammonia. As a ba sic rule, the warmer the water, the higher the percentage ratio of NH3 to NH4+, therefore, most commonly warm water fish species have a high er tolerances for ammonia than do 18

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cold water f ish. For most fish, un-ionized ammonia concentrations should be held below .05 mg/L (Timmons, et al., 2002). Table 2: Percentage of Free Ammonia (as NH3) in Freshwater at Varying pH and Water Temperature pH 10C (50F) 15C (59F) 20C (68F) 25C (77F) 7.0 0.19 0.27 0.40 0.55 7.1 0.23 0.34 0.50 0.70 7.2 0.29 0.43 0.63 0.88 7.3 0.37 0.54 0.79 1.10 7.4 0.47 0.68 0.99 1.38 7.5 0.59 0.85 1.24 1.73 7.6 0.74 1.07 1.56 2.17 7.7 0.92 1.35 1.96 2.72 7.8 1.16 1.69 2.45 3.39 7.9 1.46 2.12 3.06 4.24 8.0 1.83 2.65 3.83 5.28 8.1 2.29 3.32 4.77 6.55 8.2 2.86 4.14 5.94 8.11 8.3 3.58 5.16 7.36 10.00 8.4 4.46 6.41 9.09 12.27 8.5 5.55 7.98 11.18 14.97 (Timmons, et al., 2002)` Nitrite is the intermediary prod uct of nitrification between ammonia and nitrate. Although nitrite can quickly be converted to nitrate through the use of ozone or a biofilter in an aquaculture system, it is an ongoing problem due to its constant production Therefore frequent monitoring is vital if acceptable limits are not to be exceed ed. Nitrite has an extremely acute affect on fish in that it adjust s the ability of hemoglobin in the fishes blood to transport oxygen (Timmons, et al., 2002). In the bloodstream, nitrite oxidizes iron in hemoglobin, from its ferrous to its ferric state. The result is called methemoglobin, resu lting in the blood having a brown 19

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color. Nitrate is converted to and is the end product of nitrification. It is the least toxic to fish in the system an d in aquaculture system; nitrate is normally removed through water exchanges. PH The pH value of water is the negative logarithm of the hydrogen ion concentration (Timmons, et al., 2002). The measure can range from 0 to 14, with 7 representing neutral. Expo sure to extreme pH or rapid pH change can be lethal to fish. pH also has a number of indirect effects on fish through its interactions with other variables in aquaculture. pH controls a number of solubility and equilibriu m interactions, the most important of which, in aquaculture, is the ratio of ionized to un-ionized ammonia (Timmons, et al., 2002). Commonly in commercial aquaculture operations adjustments to pH are made using common vinegar to increase acidity, and sodium bicarbonate, or ba king soda, to decrease it. Alkalinity Alkalinity is defined as the total qu antity of titratea ble bases in water and is expressed in terms of mg/L (Tim mons, et al., 2002). The primary ions contributing to alkalinity are carbon ate (CO3-) and bicarbonate (HCO3-). 20

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I n practice, alkalinity is measured through a titration with sulfuric or hydrochloric acid to a methyl orange endpoint with a pH of 4.5 (Timmons, et al., 2002). With aquaculture sto cking density increasing, and system water retention time lengthening as cr oppers attempt to increase yields; the pH / alkalinity rela tionship has become a pressing issue to system health. Alkalinity is one of the more easily adjusted system components, merely requiring the addition of sodium bicarbonate (NaHCO3), a compound also known as baking soda. In many commercial systems, for every pound of feed added, a quarter pound of sodium bicarbonate is added (Timmons, et al., 2002). Carbon Dioxide and the Carbon Cycle Carbon dioxide is one of the most soluble gases in water; however, water normally has a very low concentra tion of it. In aquaculture systems the primary source for carbon dioxid e is respiration and decomposition, with only a small portion of CO2 comi ng from atmospheric diffusion. High levels of carbon dioxide in the wate r make diffusionary excretion of the gas through the fishes gi lls much more difficult, resulting in increased levels of the gas in the fishes blood stream which lowers the pH of the blood plasma (Timmons, et al., 2002). This condition is called respiratory acidosis. This condition results in the hemoglobin in the blood becoming unable to carry normal quantities of oxygen and can result in respiration 21

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d istress even if the water may contain high levels of dissolved oxygen due to the Bohr Shift (Timmons, et al., 2002). The upper limit of dissolved carbon dioxide normally accepted in aquacult ure systems is 20 mg/L (Timmons, et al., 2002); however this level is species dependent. Salinity Commonly, water is described as fresh, brackish, or salt; these however are not specific terms, instea d just generalizations about salinity. The definition of salinity is the tota l concentration of dissolved ions in water, reported as parts per thousand (ppt). The primary contributors to salinity are calcium, sodium, pota ssium, bicarbonate, chloride, and sulfate. Each species of fish has its own optimal range of salinity. Most commercially grown freshwater species thrive at 4-5 ppt (Timmons, et al., 2002). Fish are able to maintain the co ncentration of dissolved salts in their fluids by regulating their uptake of ions and restriction of ion loss in a process called osmoregulation. Osmoregulation, however, is a great energy expense and comes at the cost of other functions such as growth. If the salinity strays too far from the fishes optimum range it becomes impossible for the fish to maintain homeostasis and they will expire. However, in cases of certain fungal disease, moderate, temporary, increases in salinity may eliminate the outbreak. 22

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Filtration The filtration component of an aq uaculture system is among its most vital. An aquaculture system without a filtration unit could conceivably raise fish, but the system would support so few organisms it would not be worth operating. Through filtration, an aquaculture system can be made capable of supporting far more orga nisms than possible under natural conditions. Solids The solids which accumulate in a ll aquaculture systems are entirely waste products. They result most commonly from uneaten feed, fecal matter, algae, and biofilm from biologic al filters. In a recirculating system waste solids influence the efficiency of all other processes. Solids wastes also harbor and serve as breeding grounds many forms of pathogens which can negatively affect the system and its occupants. Therefore the removal of solids is a critical proce ss in successful aquaculture systems. The solids in an aquaponic system are di vided into three categories: settlable, suspended, and dissolved. Settleable and suspended solids can generally be removed mechanically or through protein skimming; other means are required for the removal of dissolved solids. All aspects of a recirculating aquaculture system are adversely affected by suspended solids. Suspend ed solids have both inorganic and 23

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organi c components. The organi c component, known as volatile suspended solids, contributes to oxygen consumption and fouling problems. The inorganic components co ntribute to sludge formation. Therefore the mitigation of suspended solids is the first aspect of any efficient filtration system Suspended solids result from feces and uneaten food and can produce biofloc by harboring living bacteria. The size of the suspended particles will vary greatl y from several centimeters to just a few microns. Such solids are characterized and classified by size. The term "fine solids." will be used herein to identify particles that do not readily settle in the water column. Large pa rticles are easily removed through mechanical filtration methods, such as filter bags, and settling tanks. Fine particles are most simply removed from the system by foam fractionation. Foam fractionation is an efficient, cost effective method of removing small particles and dissolved organi c wastes among other wastes known as surfactants from water, while, at the same time, in creasing dissolved oxygen levels. Foam fractionators in th eir most simple form consist of a column of water in a cylinder which is highly aerated at its base. 24

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Figure 1 Co-current foam fractionator schematics The aerated water is allowed to ex it the column through an outflow near the top of the cylinder. The surf actants and other particles will bond with the air bubbles and rise to the top of the water co lumn with the air bubbles and form foam. More simply in a foam fractionator water and air are mixed together in a column, as the air bubbles travel upward through the water column; they collect proteins and bind organic waste particles on the bubble walls. These bubbles rise, forming a foam layer on the surface of the water, as this layer grows; it flows out of or is removed from the column, separating it from the water inside the vessel. This 25

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method of fi ltration is also known as protein skimming. In terms of filtering particles of varying size, granular medi a filters are the most effective. Such filters are capable of removing solids as small as 20 m, however, they are expensive systems and require a cons iderable level of maintenance. Granular media filtration utilizes the passage of water through granular media and deposition of solids onto the media. The mechanisms that remove the particles are straining, sedimentation, intact interception, adhesion, flocculation, physical abso rption, and biological growth. Figure 2 Basic granular media filter schematic Biological filtration. The primary purpose of a biofilter is for the removal of nitrogenous wastes. The process of ammonia remova l through biological filtration is called nitrification and consists of the oxidation of ammonia to less volatile 26

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compounds such as n itrate. An ideal biofilter would remove 100% of the ammonia concentration in an aquacultural systems water, the filter would produce no nitrate and occupy a small footprint, it would utilize inexpensive media and require little ma intenance. Naturally there is no one filter type that meets all of these criteria. Figure 3 Powered return biofilter schematic One simple bio-filter design commonly employed in small scale aquaculture units is the standing drum filter, diagrammed in figure 3. In such a form the filter consists of a co ntainment drum with both an inlet for effluent laden system water to enter and an outlet leading to a pump to return the water to the system afte r passing through the filter. In the bottom of the drum a screen of filter is fitted to prevent the filter material from entering the water return pipe. The filter material usually consists of any inorganic, non-biodegradable ex panded material, with a focus on maximizing the materials surface area. When used, nitrogen fixing 27

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bacter ia will colonize the surfaces of the filter ma terial greatly increasing the volume of effluent laden water ex posed to the bacteria allowing for more rapid nitrification. Water quality control In a recirculating aquaculture system, the time that water is retained in the system is greatl y increased over other methods of aquaculture. For this reason water qual ity control is vital for the success of the system. While a recirculating syst em does retain system water for extended periods of time, a primary method of maintaining water quality does include periodic partial water ch anges. In this method, system water usage is greatly reduced and system input cost is lowered. Small systems Small scale aquaculture systems have existed for decades. The designs of the systems are extremel y varied. Just as varied are the purposes of the systems, ranging from recreation to profit. Small systems face challenges not encountered in la rger operations. Generally speaking they are not able to make use of all developments in aquaculture technology, restricted by their output capacity reducing their profitability, and the viable capital input level. In addition to producible biomass, actual physical growth size attainable may be limited in some species. Meanwhile, other species may simply not be capable of surviving in 28

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smaller systems. Another challenge fa ced in operating a small system is the speed at which changes within the system can occur. In a small system all changes can occur much more rapidly and therefore, much more severely affect the culture specie s than in a large system. Everything from nitrogen loads to temperature can change extremely rapidly in a small system. Therefore, small systems must be even more closely monitored than their larger counterparts. However, small scale aquaculture systems are afforded nu merous cost-saving advantages not feasible to large-scale operations. In small scale systems, recycled materials may be efficiently incorporated into unit design in a cost-saving manner. Common household items, su ch as recycled plastic sixpack beverage rings, may be utilized as biofilter media, as is done with the Texas Agricultural Extension Service water melon research system (Burns, 1997). 25 years ago Robert Rodale, a pr oponent of domestic gardening and farming, asked the question "is it possible for a family to grow its own fish just as it is to grow vegetables in the garden?" Considering that fish is one of the healthiest and most nutritious sources of protein available. He determined that the answer should be, "yes". With continually increasing costs of seafood and growing concern over its quality and safety, Rodale's question and the answer to it, is more relevant than ever. 29

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Initial small-scale aquacultural research was carried out at the Organic Gardening and Farming Research Center in eastern Pennsylvania. The first systems were small hand dug ponds stocked with carp and catfish. The fish were fed a combination of cable and garden scraps. These early systems, however, soon became fouled and resulted in large numbers of dead fish (Van Go rder, 2003). Soon after, The Rodale Aquaculture Project, coordinated by Steve Van Gorder, was founded to scientifically study the va rious methods available to grow fish on a small scale. Studies initially carried out by the project included fish culture in pools, greenhouses, and farm ponds. In addition, this research project first investigated the viability of tilapia in small-scale production systems, as well as initial integratio n of fish culture with hydroponic vegetable production. Later studies undertaken by the Rodale aquaculture project included fish culture in inflatable sw imming pools, which were found to be extremely productive containment systems for home recirculating aquaculture systems. After much study, it was found that a 1 m containment system could provide eno ugh tilapia to meet a familys need throughout the course of a single year (Van Gorder, 2003). Species selection for aquaculture systems The introduction of fish stock into cu lture systems is a critical phase in overall operation management. T he selection of which species to 30

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populate a system wi th is depend ent on many factors, such as, availability, initial price, market value, system design, feed type, physiology, and legality. In many st ates, permits must be obtained for importation, transportation, and stocking of fish. In addi tion, if purchased for grow out and the commercial sale, health certification from origin of purchase is generally required (Lauch 2002). Certain species are capable of growing to harvest size only under certain condition an d system size, if grown in a smaller than ideal system they may never reach the desired size or may even simply pe rish. In addition different species are able to grow at varying density depending on the system size; for example, tilapia are capable of growing densely in small and large systems, while trout can grown densely but only in large systems. The temperature range of the system is also critical in spec ies selection. While many systems are capable of being heated or chille d to optimally fit the temperature requirements of the desired species, the additional costs and inherent risks associated with such an adaption rend er the system inviable. In addition, bio security is at its weakest when intr oducing fish into a system. At no point during the life of the culture is there a greater chance for parasitic contamination of the culture unit. Ne ver during the stocking of a system should water from the transport vessel be introduced into the containment system. A simple saline bath is an easy and inexpensive 31

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means to r educe the chance of cross-contamination when introducing new culture organisms (Lauch, 2002). Notable species common to aquaculture Redclaw crayfish Cherax quadricarinatus Figure 4 Redclaw crayfish (Nelson, 1998) Australian Redclaw crayfish are primarily herbivorous fast growing crayfish. This is an advantageous tr ait in aquacultural systems due to reduced feed costs. The Redclaw reaches maturity at a length of 9-10 inches in a year or less (Nelson, 1998). Their name comes from a bright red streak on the males claws, while the carapace on both male and female specimens is blue. Their nonaggressive nature makes them suitable for crowded culture techniques and an ideal species for polyculture. Redclaws provide a higher yield of meat than most crayfish and exhibit a 32

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hi gh feed conversion rate. There exis ts a wide non food market as well, both in the pet and scientific su pply field. Redclaw have few health concerns, and are susceptible to few diseases and parasites. They will thrive in 70-90 OF water and are usually grown with goldfish, koi, or tilapia. Red Claw will consume excess food, algae and debris; aiding in keeping the tank clean. Table 3: Redclaw environmental survival requirements Temperature: Below 70 slows growth and below 50 is fatal Ph: 6.5-9 Hardness: 80-200 mg/l Ammonia: <.5mg/l Nitrite: >.3ppm mg/l Alkalinity: <100 ppm Chloride: 50ppm mg/l (Nelson, 1998) Rainbow Trout Oncorhynchus mykiss 33

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Figure 5 Rainbow Trout (Nelson, 1998) Trout farming is the oldest form of commercial fish production in the United States, dating back 150 years. Worldwide, trout farming produces millions of pounds of fish per year (Nelson, 1998). There are fourteen species of trout found in North Americ a, with rainbow and brook the most popular for cultivation. While commonly cultured for release, the brown trout is not as well suited to grow out for commercial food production. Temperature is among the most critical factors in raising trout. Trout thrive in waters between 50-68OF, with the ideal temperature being 64 OF (Nelson, 1998). Temperatures above 75 OF can be lethal. Research on trout nutrition has been conducted for nearly forty years. Trout require a diet high in animal protein. Fry and fingerlings require even higher protein content in their feed than adults. Fry and fingerlings should be fed a diet consisting of 50% protein and 15% fa t while mature trout should be fed 40% protein and 10% fat (Nelson, 1998). Trout are susceptible to many pathogens and environmental alterations. Fortunately most of their diseases are easily diagnosed and treated. Factors affecting trout 34

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stock ing rates include filtration, co ntainment type, and temperature. In raceway culture, trout may be stocked as densely as 10 lbs per cubic foot of water (Nelson, 1998). In the United States most large culturists rely on brood fish farms to supply eggs. Incuba tion of trout eggs is temperature dependent. After fertilization, Rainbo w trout eggs hatch in approximately three weeks when kept at 55 degrees. Farmed trout are usually harvested when they are 7 14 inches long at a weight of to 1 lb. This can be achieved in as little as 7 months under the correct culture conditions (Nelson, 1998). Table 4: Rainbow trout environmental survival requirements Temperature: 50-68OF Ph: 6-8 DO: 5-12 mg/l Alkalinity: 50-250 mg/l Co2: 0-20 mg/l Hardness: 50-350 mg/l Chloride: 0-1500 mg/l Salinity: 0-3 ppt Nitrite: 0-.2 mg/l 35

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(Nelson, 1998) Tilapia Figure 6 Tilapia (Nelson, 1997) Tilapia, the colloquial name for the fishes of the tilapiine cichlids, comprised of the families Oreochromis Sarotherodon and Tilapia, are the most widely cultured family of fi sh in aquaponic systems worldwide. Production in 2006 alone exceeded 2, 381,237 metric tons (Fitzsimmons, 2008). Originally found in Africa, thes e members of the cichlid family are now cultured worldwide. Tilapia are easi ly bred in captivity and thrive in a wide range of water conditions and temperatures. Tilapia can be raised effectively in small systems, offering little space, as would be found in the home. Most tilapia can be fed a wide variety of foods, even consuming table scraps and vegetation. They exhi bit extraordinarily efficient feed to body mass conversion ratios, as high as 1.5:1, converting 1.5lbs of feed into 1lb of body mass (Burns, 1997). Under ideal aquacultural conditions, tilapia can grow to a weight of 2.5 lb s in six months (Nelson, 1997). Tilapia are resistant to most diseases and pa rasites and can survive an extremely 36

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w ide range of conditions, making them one of the easiest and most productive fish to culture. Table 5: Tilapia environment al survival requirements Temperature: 64-90 OF Ph: 6-8 DO: 3-10 mg/L Alkalinity: 50-250 mg/l Co2: 0-30 mg/l Hardness: 50-350 mg/l Chloride: 0-5000 mg/l Salinity: 0-10 ppt Nitrite: 0-.8 mg/l (Nelson, 1997) Channel Catfish Ictalurus punctatus 37

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Figure 7 Channel catfish Catfish rank among the most commonly cultured species in America, with millions of pounds produced every year. In small aquaponic systems catfish are able to be raised with other species. Catfish are naturally predatory in na ture, but will readily consume pelleted feed. Catfish exhibit extremely effi cient feed to body mass conversion, under ideal conditions, converting 1. 5 pounds of feed into 1 pound of body mass (Nelson, 1998). In recirc ulating culture systems catfish can grow to a weight of 1 pound in five months, and can be densely stocked provided adequate aeration of the tank. Table 6: Channel catfish environmental survival requirements Temperature: 70-90 OF Ph: 6.5-9 DO: >4 mg/L Alkalinity: 50-100 mg/l Co2: <15 mg/l 38

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Hardness: 50-100 mg/l Chloride: 0-5000 mg/l Salinity: 0-5 ppt Nitrite: 0-.8 mg/l (Nelson, 1998) Mosquitofish Gambusia affinis Figure 8 Mosquitofish (Webb, 1999) The mosquitofish is a widely ranging species found naturally throughout the southern half of the United States west of the Appalachians and east of the Rocky Mountains. It has, however, been introduced widely across the United States, currently being found in 48 of 39

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the 50 stat es, including Alaska, as well as globally (Webb, 1999). Naturally common in vegetated ponds, lakes and sluggish streams, aquacultural production of mosquitofish has been on the rise. The mosquitofish have become a valuable production specie s, with the primary consumer being mosquito control groups, who utilize t he mosquitofish to control mosquito larva populations in stag nant bodies of water. Mosquitofish spawn continuously throughout warmer weather After a gestation period of 21 28 days a brood of 14218 live youn g are born, depending on female body size. Sexual maturity is reached within 28 days of bi rth (Webb, 1999). Mosquitofish are omnivorous and will consume practically anything they can fit within their mouth Table 7: Mosquitofish environmental survival requirements Temperature: 60-80 OF Ph: 7-8 DO: 2.5-10 mg/L Alkalinity: 50-250 mg/l Co2: 0-30 mg/l Hardness: 50-100 mg/l Chloride: 0-5000 mg/l 40

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Sal inity: 0-11 ppt Nitrite: 0-.8 mg/l (Webb, 1999) 41

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Hydroponic plant culture The culture of plants without soil is referred to as hydroponics. Hydroponic farming method s have existed in various forms for thousands of years (Nelson, 1997). The premise of hydroponic cropping is the growth of plants in nutrient free substrate. Hydroponically cropped plants receive all necessary nutrients, normally acqu ired through the roots in soil, by means of a nutrient rich solution rat her than from the substrate in which they are grown. In some forms of hydroponics, plants are grown without any form of substrate and mechanical devices are used to maintain the plants position, ra ther than the plants' own root systems (Resh, 2004). Hydroponics presents many potentia l opportunities for a producer over normal soil based agriculture me thods. The nutrient solution in a soilless grow system can, in cases of contamination, such as with disease, be drained away and sterilized or replaced. The same holds true for the grow medium, if one is used, it can be replaced or sterilized with relative ease. However, in soil based agricu lture, there are few options for sterilization. In a soilless culture, beca use of the use of a nutrient solution, the supply of nutrients is homogeneous and areas of low nutrient concentration do not occur as in soil culture. This is extremely beneficial for the grower. The plants do not need to develop a root system as 42

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extensiv e as is needed in soil, and are constantly supplied with the nutrients they need, resulting in more rapid vegetative growth. Also, because of the consistent nutrient su pply, a greater number of plants are able to be grown in a given area of space, limited only by lighting and natural space requirements needed fo r upper plant growth. Because of the lack of soil, and the extent of the growers control over the entire system, hydroponics is fe asible in non arable areas, and has even been practiced in space. Seeding Plants intended for eventual hydr oponic culture should be started from seeds. Whether started in-hou se or purchased as seedlings is a decision influenced by cost, availabi lity, and time. An additional and critical factor in this decision is possible infestation of parasites from purchased seedlings. If operating a growth system reliant upon a staggered planting regimen, a grea ter potential exists to introduce parasites by utilizing purchased seedli ngs (Resh, 2004). The most reliable option for system bio-security is to start seedlings in-house. There are many methods by wh ich seeds can effectively be sprouted. Seeds intended for sprout ing require warm conditions and a high moisture level. If system co nditions are compatible, seeds can be directly sown into the hydroponic system. However, during their initial 43

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sprouti ng period, seedlings require no nutrients from their environment, therefore, direct seeding into a hydrop onic system would result in an area of the system being occupied but no t utilized by the plants contained within. In most systems the more economical option would be to externally sprout the seeds, then transplant the seedlings into the hydroponic system. Sprouting systems for seeds ar e exceedingly simple. Seeds can easily be sprouted in numerous materials. Selection of growth medium is critical when designing a sprouting system intended for transplanting. Whichever medium is selected, the sprouted seeds must be able to be removed from it with li ttle or no root damage. If Rockwool cubes are utilized in the primary hydroponic grow system, the simplest method of seedling propagation is to sow the seeds directly into the Rockwool cubes or, if used, Rockwool slab s. Prior to initial seeding, the Rockwool should be thoroughly sa turated in water. Then, when of sufficient size, the cubes or slabs may be transferred into the primary grow system. The seedlings need not be exposed to nutrient solution until after sprouting (Barker, et al., 2007). When seeding, it is important to note the expected germination ratio for the seeds which you are planting. The incorporation of this planting info rmation enables the more accurate hedging of planting quanti ties for non-fertile seeds (Jones Jr, 2005). Growth temperatures 44

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Proper growth in plants, requ ires a daily temperature change, optimally a nighttime temperature of 10F lower than the day temperature produces the best grow th results (Jones Jr, 2005). Low temperature will result in decreased pl ant growth rates, and may result in mis-colored leaves. If temperature is too high, poor quality plants will result; new growth will not be sturdy. Light If plants are to be grown in less than total sunlight, supplemental lighting must be provided. The two ma jor processes that are performed by green plants using light are transpirat ion and photosynthesis. Both of these processes required great amounts of energy provided by lights; however, only photosynthesis result s in the plant retaining any of the energy. Light also has influence over other processes such as flowering, seed germination, fruit production, and certain stages of developmental growth. Transpiration in plants is the process by which plants give off oxygen and water vapor through their stomata. In this process solar energy is only used to transform liquid water into water vapor. Photosynthesis, on the other hand, is a process which occurs in the chloroplasts, water and carbon dioxide are combined utilizing light to assist in the reaction. The result from the process is the formation of carbohydrates, which are stored in t he plant as starch, cellulose, and may 45

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prov ide carbon skeletons for plant stru cture. The carbohydrates stored by the plant are converted to energy by respiration. Light, as it comes from the sun, is part of the spectrum of electromagnetic radiation. Only part of the spectrum is e ffectively used in photosynthesis and this is a bandwidt h in the visible spectrum known as Photosynthetically Active Radiation (PAR). Chlorophyll, appearing green to the eye, is proof that much of the green light is reflected. Most of the red, blue, indigo, and violet wavel engths are absorbed and utilized in photosynthesis (Jones Jr, 2005). Inadequate light or spectral defi ciency will result in a number of responses from the plants. Indirect light placement will result in plants, stretching and growing towards the light. Commonly, plants will become discolored, growth will be stunted, or fruit production may not occur. Artificial lighting is not capabl e of producing the full spectrum of light produced by the sun. However, as plants do not require the entire spectrum, adequate artificial lighti ng can be achieved. The goal of artificial lighting is to provide light at the highest intensity possible with the broadest spectrum available. The draw backs of artificial lighting are the costs of the lights themselves, the energy required to run them, and the possibility of compromising the needs of the plants. 46

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The placement of the lamps is rela ted to the intensity of the light provided. If the lamp is extremely cl ose, the intensity of the light will be greater; however, it is possible for it to be too intense for the plant to survive. The farther the lamp is from the plant, the broader its light is spread and less intense is its power. Increased intensity and coverage can be facilitated through the use of a light mover to relocate light throughout the course of the day. Also, utilizatio n of reflective paint or reflective surfaces on and around the grow area will minimize light loss. There are many types of lighting which will result in plant growth. Although inexpensive and readily available, incandescent light bulbs are not sufficient for sustained plant grow th. They provide neither the intensity nor spectrum of light required for plant growth. Fluorescent light tubes are available in a broader spectrum of co lors than incandescent bulbs. Some of the types of fluorescent bulbs available include white, cool white, warm white, plant bulbs, daylight and full spectrum (Jo nes Jr, 2005). A combination of cool white and warm white bulbs offers a broad enough spectrum of light for numerous variet ies of plants (Jones Jr, 2005). Fluorescent bulbs have the benefits of being inexpensive, long-lasting, and readily available. Fluorescent ligh ts, however, are relatively low in intensity and must be positioned close to the plants; more florescent lights must be utilized for large beds th an if other lighting methods were implemented. 47

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High-intensity discharge lights ar e the choice of most commercial hydroponic croppers. The standard varieties of HID lamps are mercury vapor, metal halide, and high-pressure sodium. HID lamps create large amounts of heat, and in warmer clim ates, ventilation of grow areas may be necessary. However, in colder climates, they can be used as a means of partially heating a greenhouse. HID lamps also require large amounts of electricity, and therefore are mo re expensive to operate. Mercury vapor bulbs are popular for vegetative growth due to their high-intensity ultraviolet light. Mercury vapor lights are deficient however, in orange and red spectrums (Jones Jr, 2005), which are needed for flowering and fruiting in most plants. High-pressure sodium lights are very efficient longlasting and strong in the yellow red spec trums. They do lack, however, in the blue spectrum of light, which is required for vegetative development (Jones Jr, 2005). They are very g ood choice however, for the grower focusing on flowering plants. Metal halide lights, which essentially are a combination of the other two forms of HID lights, offer a wide light spectrum with ample blue light for vegetative growth and are more efficient than Mercury vapor lights (J ones Jr, 2005). Fo r an all-around single lamp, a metal halide HID would be the best choice. Minerals and essential elements 48

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Macronutrients Nitrogen (N) The discovery of nitrogen as an essential nutrient to plants is credited to Nicolas-Thodore de Saussu re in 1804 (Barker, et al., 2007). de Saussure additionally determined that nitrogen was obtained by the plant mainly from the soil, when the commo nly held belief of the period was that plants primarily obtained nitrogen from the air (Barker, et al., 2007). Metabolism and constituents Nitrate Assimilation The major sources of nitrogen for plants are nitrate (NO3 -) and ammonium (NH4 +). Nitrate is the primary of these two sources (Barker, et al., 2007). Nitrogen, in the form of nitrate, is highly mobile within the plant and is stored in vacuoles. Utilizat ion of nitrate, however, cannot occur prior to the nitrates reduction to ammonium. Every plant cell has the capacity to reduce nitrate into nitrite (NO2 -) utilizing the energy and reductant provided by photosynthesis in green tissues and respiration in non-green tissues. During nitrate redu ction a two electron transfer takes place reducing nitrate to nitrite. Wi thin the chloroplasts is located the enzyme nitrate reductase (reduced ferredoxin) as well as in the proplastids of nongreen tissues whic h reduces nitrate into ammonium, 49

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ut ilizing energy and reductant produced by photosynthesis in the leaves of the plants and cellular respiration in non-photosynthetic cells (Barker, et al., 2007). The reduction of nitrate into ammonium results from the transfer of six electrons. During the transforma tion no intermediates are formed, the entire conversion occurring in one el ectron transfer. The process is extremely energy consuming utilizing the equivalent of 15 mol of ATP for each mol of nitrate reduced (Barker, et al., 2007). Nitrate assimilation in roots requires as much as 23% of the respiration energy as compared with 14% for ammonium assimilation. Nitr ate however, unlike ammonium, can be stored in plant cells without toxic effect (Barker, et al., 2007). Ammonium Assimilation The primary mechanism of assimilation and detoxification of ammonium involves the metabolism of ammonium into amino acids and amides. Ammonium assimilation occurri ng in mitochondria results with the effort of a single enzyme, glutamic acid dehydrogenase. When occurring in chloroplasts, ammonium assimilation utilizes the ammonium produced from the reduction of nitrite with the enzymes glutamine synthetase and glutamate synthase (Barker, et al., 2007). Content 50

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Plants w ith a sufficient supply of nitrogen will have a dry weight consisting of approximately 2.00 to 5.00% Nitrogen, varying by species (Barker, et al., 2007). Approximately 85 % of the total nitrogen in plants is in the form of proteins, nucleic acids re presents an additional 5% of weight by nitrogen, with the remaining nitrogen in the form of low molecular weight organic compounds (Barker, et al., 2007). Generally younger plants have a higher percentage of nitrogen by weight than older plants (Jones Jr, 2005). Function Nitrogen is more essential than any other element on plant growth (Jones Jr, 2005). Nitrogen not only a ffects plant growth but also directly impacts fruit yield and quality. Nitr ogen is one of the primary constituents of many amino acids and proteins in plants (Barker, et al., 2007). Atmospheric nitrogen is not utilized by plants, instead nitrogen is taken in, in the form of nitrites by the roots. Deficiency symptoms A lightning of the green color normally associated with healthy plants is often the first sign of a ni trogen deficiency. This occurs due to translocation of nitrogen from the leaves to other areas of the plant (Barker, et al., 2007). Overall a shorta ge of nitrogen results in restricted growth of the plant organs, roots, stems, flowers, and fruits (Barker, et al., 51

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2007) On young leaves, the yellowing will first appear away from the growing tip (Rebecca, 1998). During the growth cycle, deficiency of nitrogen will result in existent nitrogen being mobilized from lower leaves to younger leaves (Barker, et al., 2007). Commonly in healthy plants more than 75% of the leaves stock of nitrogen is contained within the chloroplasts, thus rapidly making visi ble decreases in leaf nitrogen content due to translocation. If the defici ency of nitrogen continues or worsens, the discoloration will spread to all le aves, eventually killing them (Jones Jr, 2005). Plants subjected to nitrog en deficiency will increase root development in an attempt to miti gate the nitrogen deficiency by drawing more nitrogen from the soil (Jones Jr, 2005). Excess symptoms. Excess nitrogen is as dangerous for plant health as is nitrogen deficiency. After initial nitrate assimilation and translocation, nitrogen exists in the form of ammonium with in the plant which can be extremely toxic to the plant (Barker, et al., 2007). Nitrogen excess in plants results in foliage that is more susceptible to herbivory and reduced overall fruit quality (Jones Jr, 2005). Plant stems will grow rapidly but be extremely weak. Plants will require longer periods of time to reach maturity and reproduction progress will be stunted (Rebecca, 1998). 52

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Phosphorus Function Phosphorus plays a cr itical role in the energy transfer system of plants and is a critical constituent of adenosine diphosphate (ADP) and triphosphate (ATP) (Jones Jr, 2005). Outside of its vital role in energy transfer, phosphorus is an essential structural component of phospholipids, nucleic acids, nucleotides, coenzymes, and phosphoproteins. Phospholipids are an important part of membrane structure within the plants. Genes and chromosomes requir e nucleic acids to assist in the transfer of genetic material from ce ll to cell. Utilization of phosphorus occurs in the fully oxidized and hydrated form, orthophosphate (Barker, et al., 2007). Phosphorus stimulates growth in all periods of a plants lifecycle, stimulating root growth, blooming, speeds seed growth, and hastens maturity (Rebecca, 1998). Therefore, a phosphorus deficiency considerably slows plant growth and productivity. Content The phosphorus content in dried plant matter ranges from 0.1 to 1% by weight (Barker, et al., 2007). In young plants, the concentration tends to range more closely to 1% (Jones Jr, 2005). 53

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Deficiency symptoms Suppressed growth and delayed matur ity are two of the first and most apparent signs of a phosphorus deficiency (Barker, et al., 2007). Continued deficiency can result in discoloration of older leaves, and however similar discoloration can also be brought about by other causes and is generally considered an unreliable indicator of phosphorus deficiency. Occasionally the discolor ation will be distinctively purple, however this is also a possible indicator of a nitrogen deficiency (Rebecca, 1998). Phosphorus content of less than 0.2% of the dried weight of the plant's foliage is a signal of ongoing phosphorus deficiency (Jones Jr, 2005). Excess symptoms Recent research is showing that excess phosphorus, on the order of greater than 1% of dry weight, will resu lt in phosphorus to xicity (Jones Jr, 2005). The toxicity is most likely an indi rect effect as much as it is an effect on the function of other elements. Phosphorus excess is a problem primarily associated with soilless cu lture, under conditions where generalpurpose fertilizer, instead of elementally specific fertilizer, is utilized (Jones Jr, 2005). This occurs due to how readily the phosphorus is taken in by the plant, in an elementally specific system, the quantity of phosphorus available to the plants can be contro lled. Phosphorus toxicity can prevent 54

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the uti lization of, and therefore result in the eventual deficiency of iron in developing leaves (Rebecca, 1998). Potassium Growth mediums containing or supplemented with potassium have long been known to contribute to cr op productivity. However, the first person to identify the actual presence of potassium in plants was Martin Heinrich Klaproth in 1762 (Barker, et al ., 2007). His resear ch supported later studies by Carl Sprengel, who first surmised that plants utilized inorganic nutrients to fuel growth and therefore utilized potassium. Research from these studies resulted in the first potash mines being sunk in 1860 in Stassfort, Germany to supply fertil izer (Barker, et al., 2007). Content In plants, the predominant inorganic element is Potassium (K+). Healthy plants contain 1.25% to 3% potassium by dry weight, however, there are plants species that require po tassium levels of up to 10%. (Jones Jr, 2005) Potassium is readily taken up by the roots, even in levels greater than metabolically needed by the plant. Most fruiting crops have a high requirement for potassium. Function 55

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Potassi um is a believed to be important for carbohydrate synthesis and movement within the plant (Jones Jr 2005). Plants are entirely unable to grow without a supply of potass ium. If a supply of potassium in unavailable during sprouting, the plan t will quickly perish after depleting the potassium reserves of its seed. Potassium ions activa te many enzymes within plants. Many of the enzymes that potassium activates, could theoretically be activated by Ammonium (NH4 +), Rubidium (Rb+), or Cesium (Cs+), however, under natural cond itions, the concentration of these species is low and will never reach the activation concentration required for the enzymes (Barker, et al., 2007). It is assumed that enzyme activation occurs when K+ binds to the enzyme surface, changing the enzymatic conformation (Barker, et al., 2007). Potassium is also utilized in polypeptide synthesis in the ribosomes, a process requiring a high K+ concentration (Barker, et al., 2007). Potassium is readily taken up by plants. The plant membranes have various selective K+ channels. One of these ch annels, the low affinity channel, transports K+ when the electrochemical potential of the cytosol, or intracellular liquid, is lower than in the outer solution. The import of K+ increases the electrochemical potential of the cytosol, eventually resulting in an equal potential as the outer solution and ceasing K+ transport (Barker, et al., 2007). Pumps locate d in the plasma membrane maintain the electrochemical potential of the cytosol through the release of 56

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Hydrogen ions (H+) (Barker, et al., 2007). High affinity transport of potassium occurs as a cotransport, where K+ is transported with cationic species such as H+ or Na+, with the complexes behaving as a bivalent cation, providing a stronger force along the electrochem ical gradient. Due to the existence of these selective transport systems, K+ transport occurs very rapidly. Deficiency symptoms Symptoms of a potassium deprived plant include slowed growth and reduced turgor (Jones Jr, 2005). In itially yellow to brown spotting of the leaf edges may occur (Rebecca, 1998). Further deprivation of potassium can result in leaf scorch where the edges of the leaves will appear to have been burnt. In some plants potassium deficiency will lead to reduced stalk strength. If occurring during frui ting periods, the seeds and fruit of the plants may shrivel (Rebecca, 1998). Excess symptoms There is little evidence showing potassium, in excess, as dangerous to plant health, however,NO3 and other anions can be used by the plant to partially regulate uptake (Jones Jr, 2005). Calcium Content 57

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With a dry weight content of 0.5 to 3%, calcium is among the most variable elements by mass in plant matt er (Jones Jr, 2005). Even its form of existence within the plants is variable by species. Calcium uptake is dependent upon rooting medium characteristics and rates of transpiration within the plant. Function Calcium is one of the primary st ructural elements of the middle lamella of the cell walls of the plant and is responsible for maintaining the structural integrity. Calcium, however, is immobile in the plants and cannot be transferred from older areas of growth to newer ones (Rebecca, 1998). Therefore, a steady calcium supply is vital to continued plant growth. Calcium also assists in the translocation of carbohydrates within the plant. Deficiency symptoms A Calcium deficiency is apparent in many areas of the plant. In the younger leaves, calcium deficiency will cause dis-colored leaf tips; in developing leaves irregular structur al development will result in torn margins and may result in decreased leaf size (Jones Jr, 2005); mature leaves will become abnormally green (Rebecca, 1998). Calcium deficiency results in reduced root grow th and existing roots turning brown. 58

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Excess symptoms Although uncommon, calcium excess is possible in plants, most likely resulting in a po tassium or magnesium defi ciency (Jones Jr, 2005). Magnesium Content Plants require different levels of magnesium depending on the stage of growth and environmental conditions. Therefore, magnesium content will range from 0.2 to 0.5%, although content may occur as high as 1% of the plants dry weight (Jones Jr, 2005). Function Magnesium serves as an enzyme activator for a number of energy transfer processes, as well as being a major constituent, and the only mineral element, of the chlorophyll mo lecule. Therefore, magnesium is vital to plant growth and development. Deficiency symptoms Magnesium deficiency makes itse lf apparent as interveinal chlorosis, first appearing in older le aves (Jones Jr, 2005). Magnesium deficiency is difficult if not impossible to correct, particularly if occurring 59

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dur ing periods of peak growth. When magnesium is deficient, CO2 fixation is reduced and therefore production of carbohydrates is accordingly reduced and plant growth and production declines. Magnesium deficiency can also result in extremely reduced plant size (Rebecca, 1998). Excess symptoms Although magnesium excess is unlike ly, research has suggested that magnesium concentrations should no t be allowed to exceed that of calcium in order to main tain proper cation ba lance (Jones Jr, 2005). Sulfur Content Although not unusual, a 1% level of sulfur content in dried plant matter is relatively high, more commo nly plant leaf content ranges from 0.15 to 0.5% (Jones Jr, 2005). Function Cystine and thiamine, both essent ial amino acids in plants, are constructed largely of sulfur (Jones Jr, 2005). Plants also utilize sulfur as a major constituent of their cell wa ll construction (Rebecca, 1998). 60

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Deficiency symptoms T he symptoms of sulfur deficiency closely resemble those of nitrogen deficiency and are easily confused A notable difference in their symptoms is that sulfur deficiency wi ll result in a lightening of the green color universally across the plant versus initially with nitrogen deficiency visible only in the older leaves (Jo nes Jr, 2005). However, due to the overwhelming similarity with nitrogen deficiency, it is most sensible to perform a plant analysis to confirm possible sulfur or nitrogen deficiency problems. Excess symptoms Because plants are able to control their sulfur uptake and are tolerant of high levels of sulfur, sulf ur excess is rarely a concern (Rebecca, 1998). Transfer of plant nutrients In practice all plant growth is hydroponic since nearly all elements absorbed by plant roots must be in a water based solution. In soil, mineral movement in the soil and root growth affect element uptake. The uptake is greatly simplified in hydroponic sy stems in which the growth medium is inert or nonexistent (Resh, 2004). Within soil elements move by diffusion from areas of high concentration to areas of low concentration. The 61

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nutr ients taken up by the plant are, naturally, those immediately present next to the roots in the rhizosphere. In a hydroponic system, the roots are exposed to nearly the full volume of available nutrients. The complex interactions of nutrient s within organic planting mediums can be greatly simplified and more ea sily controlled in an inorganic hydroponics cropping system and enable greater control of plant growth. The roots of the plants act as the highway for nutrient supply to the plants, however, essential to this transf er is water. Water is a catalyst for nearly every biological function of a plant. Within the plant water is the carrier of nutrients throughout the organism. Transpiration of water through the leaves is responsible fo r water movement upwards from the plants roots and in turn carries needed elements to growing areas of the plant (Resh, 2004). Plant cells accumulate ion concent rations higher than naturally present in their environment. Different ions are transported by diverse mechanisms throughout the plant. Io n absorption in the roots is both passive and active (Resh, 2004). Passive absorption is controlled by the passage of water into the plant roots. Passive absorption is responsible mainly for the uptake of potassium, nitrate, and chloride ions. However, the cell membranes in the roots act as an effective barrier to the entry of most ions, therefore active transporta tion must occur. This is an energy 62

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intensiv e process because the ions are taken up selectively and accumulated within the root across a considerable concentration gradient. This energy for this process is produced in the plants cells through metabolism (Jones Jr, 2005). Culture methods The origins of hydroponics can be traced back thousands of years, however, only more recently has scientific research allowed more intensive and productive method s of the field to develop. Water culture Water culture can be considered the most pure of all hydroponic growing methods. The roots of t he plants growing system are not suspended in any form of inorga nic medium; instead, they grow suspended in aerated nutrient solution The only form of support that plants receive while growing in a wate r culture is that of some sort of inorganic crown support/flotation device to hold the weight of the plant. Of the utmost necessity for successf ul water culture is proper root aeration. Whether grown hydroponically or in soil plants do require a certain level of aeration at the root s. In water culture, this may be achieved by numerous techniques. Depending on the layout of the growing beds, the hydroponic cropper may elect which method will best 63

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be sui ted. In a completely leveled growth system, forced aeration through mechanical means such as a pump or compressor can be used to bubble air into the nutrient solu tion through a perforated pipe, air stone, or venturi. This can occur either in the nutrient solution reservoir or in the grow beds themselves, dependent on depth. Alternatively, aeration can be facilitated through vertically staggered grow beds. Riffles or even spaces of complete freefall as the solution flows from bed to bed will enable aeration to occur. Nutrient flow is also of importan ce in a properly maintained water culture system. Although if allowed to si t, the nutrient solution will return to a homogenous nature as plants remove nutrients, the goal of hydroponics is to maximize output, therefore to maintain a constant balance of nutrients universally throughout the syst em, it is necessary to continuously agitate the solution to facilitate a homogeneous mixture. A commonly recognized standard of solution exchange is one full exchange per hour of the entire grow beds volume (Jones Jr, 2005). Additionally, in the design of su ccessful water culture systems the omission of light from the root growth area should be incorporated (Jones Jr, 2005). Plants are able to survive with their roots exposed to light during the daytime. However, in order to su rvive under such conditions, the roots must be maintained at 100% humidity (Jones Jr, 2005). The presence of 64

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l ight in the solution does however pres ent certain challenges. By allowing light to penetrate to the solution, algal growth is enabled, resulting in competition for oxygen and nutrients with the intended plants of the system. The most effective means to mi tigate algal growth is to cover the grow beds and any other light admitting area which holds nutrient solution with an opaque material (Jones Jr, 2005). Early methods Water culture represents one of the earliest forms of hydroponics. More modern developmental methods of water culture consisted of coated concrete troughs on which removable wooden and metal litters were erected to hold the plants and maintain humidity. 65

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Figure 9 Early water culture system design featuring raised, large, grow beds and deep nutrient troughs (Jones Jr, 2005) These litters were generally 2 to 4 inches deep and utilized wire mesh, coated in a nonreactive substa nce, as a lower plant constraint (Resh, 2004). The tray was generally fi lled with a porous material such as straw, wood shavings, coarse sawdust, peat moss, dried hay, or rice hulls. In many of the very early systems, this coarse layer would then be topped with a finer layer of medium, into whic h seeds could be directly sown. In more recent times, this multi-medium system has all but been eliminated in favor of more simple maintenance friend ly designs. In the early systems, 66

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the depth of the nutr ient solution was adjusted underneath the litter to facilitate gas exchange with the roots. Common systems Raceway One common modern variation of the water culture method is exemplified by the raceway system developed by Dr. Merle Jensen, in 1981 at the Environmental Research Laboratory at the University of Arizona, Tucson. His system consiste d of, what is now considered deep, grow beds 6 to 8 inches in depth, and had a fairly static circulation rate of 2 to 3 L per minute. Its beds were 24 inches wide by 8 inches deep by 98 feet long. The beds held 950 gallons of nutrient solution, resulting in approximately a 24 hour complete solution exchange rate (Jones Jr, 2005). The nutrient solution from t he beds was recirculated through a 1200 gallon solution reservoir, which was mechanically aerated, chilled, and then returned to the bed. The nutrient solution return line passed through an ultraviolent sterilizer in order to el iminate bacteria, fungi, certain viruses, and protozoa. Ebb & Flow Ebb and Flow, also referred to as Flood and Drain, hydroponic systems were among the first descendants of the early water culture 67

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system s to utilize inorganic growing medium. In addition, ebb and flow systems were the first systems to featur e intermittent solution flows to the plants. In its simplest form an ebb and flow hydroponic system consists of a watertight grow bed containing an inorganic growth medium, a nutrient solution reservoir, and a solution pump on a timer. The pump is timed to provide nutrient solution for only a port ion of every hour to the grow beds. When the pump is not in use, the grow beds are allowed to drain. In most systems, gravity is used to return t he solution to the nutrient reservoir. Ebb and flow hydroponic systems were among the first commercially productive systems. Th roughout the United States Pacific campaign during World War II, ebb an d flow systems were utilized to provide American forces with tomatoes and lettuce, grown in rapidly constructed production facilities near the front lines (Eastwood, 1947). In the period following the war, farmers across the southern United States began to successfully implement open air ebb and flow hydroponic tomato cropping (Eastwood, 1947). Th ese systems were so effective that by the 1960s farmers no longer needed to design their own ebb and flow hydroponic systems as standardized commercial designs were available on the market. These systems remai ned popular until the late 70s, when other hydroponic systems began to gain popularity. Although still 68

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commonl y available, the use of ebb and flow systems is primarily restricted to use in a hobby and home sized systems (Eastwood, 1947). The simplicity of ebb and flow hydroponic systems has allowed them to remain a popular option for the home and Hobby hydroponic grower. The drawbacks of the ebb and flow system are the relatively inefficient use of water and nutrient so lution, as total solution changes are periodically needed. However, the inefficiencies caused by this are limited on the small scale and predominantly affect the commercial hydroponic cropper. In order to maintain proper root aeration, the flood cycle of an ebb & flow system should be limited to twelve to thirteen minutes of every hour, depending on nutrient requirements of the crop. 69

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Figure 10 Simple pump-fed, gravity-return ebb & flow system, utilizing the pump feed as a siphon return for the ebb cycle and the overflow tube to maintain nutrient depth during the flow cycle Raft culture Raft culture, the modernization of earlier of Raceway systems, has become the predominant method of water culture. Much of the technology of raceway culture can be found in raft culture. The nutrient solution troughs are the same as in raceway culture, but instead of featuring fixed shelf like grow beds, t he beds are in fact floating on the nutrient solution supporting the weights of the plants. 70

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Figure 11 Basic raft culture schematic utilizing relatively static nutrient solution containment The rafts are most commonly constructed of 1 inch thick high density Styrofoam boards as wide as each trough and of a manageable length. The boards are drilled for holes to hold plant supports spaced as per the particular crops requirements. Most commonly, the plants are supported by plastic mesh cups, and depending on the initial method of seeding, may be rooted in Rockwool cubes housed in the cups. The rafts provide an added benefit to the hydroponic farmer in energy conservation through the insulation of the nutrient solution. However, due to the covering of the nutrient solu tions surface additional mechanical aeration is generally requ ired (Jones Jr, 2005). Raft culture systems also simplify harvesting processes. The rafts, floating within the raceways, can si mply be floated to one end of the raceway for harvest, while new rafts can be planted at the opposing end, in essence generating a production line. In systems where solution volume is at a premium, the bed can be kept with a minimal level of nutrient 71

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solut ion as in a NFT system, and increasi ng that level only to facilitate to movement of the rafts. Figure 12 Commercial raft culture raceway layout Figure 13 Commercial raft culture raceway with foam board grow beds installed Figure 14 Commercial raft culture system in use (Resh, 2004) Aeroponics Aeroponics is a method of culture derived from water culture. Aeroponics systems are the only trul y medium-less growth cultures. The roots of Aeroponics research dates back to the 1940s (Jones Jr, 2005), 72

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howev er in the modern world Aero ponics is a very valuable and productive method of hydropon ic and aquaponic cropping. In aeroponic systems the roots of the system plants are suspended within an enclosed or partially clos ed environment, where they have access to both gas and liquid nutrient so lution. The solution is provided to the plants in the form of atomized droplets. The greatest advantage of aeroponics to the hydroponic cropper is the ease of sterilization of the system. The system, having no medi a, leaves little space for bacterial growth and eases sterilization efforts. In addition, due to the shapes of most aeroponic systems, commonly circular or triangular, available growing space is increased in most situations. Figure 15 Aeroponic grow system featuring a sealead root chamber and multi direction nutrient solution fogging (Resh, 2004) Nutrient Film Technique Introduction 73

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Nutr ient film technique, although by most definitions a method of water culture, has developed to such an extent as to warrant a separate classification. Hereafter, the nutrient fi lm techniques shall also be noted as NFT. The pioneering work on the nu trient flow technique was conducted by Allen Cooper at the Glasshouse Crops Research of Littlehampton, England in 1965 (Jones Jr, 2005). The name itself stems from the most notable feature of NFT cropping, whic h is the extremely shallow depth of nutrient solution utilized in the grow beds. Later, another meaning for the term NFT, nutrient flow technique, was created and came into common usage in reference to the continuous flow of the nutrient solution in such a system. Early methods The first NFT system was constr ucted on a green house floor. The floor of the greenhouse sloped downwards toward the midline of the floor where a central trough was located. This central trough served as the nutrient solution reservoir. 74

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Figure 16 Floor plan of early nutrient film technique research system (Resh, 2004) The grow beds were ingenious in th eir simplicity. They consisted of pliable tubes of polyethylene, which, when rolled out upon the floor of the greenhouse, laid flat nor nearly flat on it. These grow tubes were laid out perpendicularly to the central trough in the floor. They were prepared for planting simply by punching holes along their upward facing sides. 75

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Figure 17 Flat Polyethylene nutrient film technique troughing material and preparation schematic (Resh, 2004) Nutrient solution delivery was fa cilitated through pumps located in the reservoir trough and delivery was controlled by gate valves at the top of each planting tube, through which a constant slow trickle of solution was allowed to flow. Although moderately successful this early method suffered from ethylene buildup which resulted in premature root senescence. The next evolution of the nutrient flow techniques changed the way in which the planting gullies and plants were assembled. The plants were started in either Rockwool cubes or peat pellets. After growing several true leaves the plants were then wrapped with a single sheet of 76

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polyethylene. T his sheet was simply pinned at its upper edge, which when paired with the sizes of the pellet s and the roots it contained, allowed more adequate ventilation for the ethylene, as diagrammed in figure 18. Figure 18 Tented nutrient film technique troughs constructed of sheet polyethylene and utilizing pelletized grow medium. (Resh, 2004) Common systems It was determined, that, for commercial production, a sturdier trough system, more than the polyethylene sheeting, was required (Jones 77

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Jr, 2005). Out of nec essity the soft gullies were replaced with hard ones, often in the form of PVC troughing material, as shown in figure 19. Figure 19 Solid PVC nutrient film technique trough (Resh, 2004) The method of planting, in small cups or Rockwool cubes, made planting and harvesting relatively ea sy. These systems were utilized for plant production but were found to be flawed when it came to producing vine crops such as tomatoes. Vine crops require higher levels of oxygen at their roots and were unable to receive that due to the closed in nature of the pipes; research found them to grow most proficiently in pinned polyethylene NFT systems featuring overhead plant support mechanisms. Therefore, solid PVC NFT cropping was useful only to the grower of lower profile crops, most commonly in horizontally biased configurations for commercial production. However, a solution arose in a me shing of the two concepts of NFT hydroponics. Research showed that vine crops could be successfully grown planted in solid troughs in Ro ckwool cubes (Jones Jr, 2005) by having a supported ventilated tented roof of polyethylene over the grow 78

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trough enough oxygen was able to rea ch the Rockwool cube and plant roots to facilitate growth. In addition, on the commercial scale, this actually resulted in a reduced component cost for the system. The individual grow channels in such a system should be provided nutrient solution at a ra te of approximately one to two liters per minute. However in moderately wide cha nnel systems it was found to be necessary to lay capillary matting down the length of the trough to facilitate even solution distribution and prevent the roots from drying out. Pipes, a frame, cascade The original NFT systems, while very functional, lacked in their ability to conserve greenhouse floor space which is always at a premium. Naturally when the space per plant pr oduced is reduced by increasing the number of plants per unit of area in a greenhouse the cost per plant is reduced. This led to the development, by Dr P. A. Schippers, of the cascade system of vertically arranged NFT channels. 79

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Figure 20 Early stand alone, vertically oriented, cascade style NFT system (Resh, 2004) This production method however is only viable for relatively short plants. It was soon discovered that this system could be made more efficient by constructing the NFT ch annels on an A-frame rather than vertically stacked. The construction of the A-frame in troduces new system challenges however. The slope must be shallow enough to prevent the plants from growing upwards into the plant immedi ately above them. In certain small systems lighting can be placed in such a way as to prevent this from 80

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occurri ng by forcing the plants to grow nearly perpendicular from the troughs. Figure 21 Cascade NFT system researched for use in low profile vegetable production (Resh, 2004) It was soon proven however, that fo r most low profile plants, such as lettuce, that production per space was nearly equal to that of raft culture techniques, with the raft culture method being much more easily maintained and less expensive to co nstruct. However, in areas with extremely limited space, A-frame construction was found to be the optimum use of space. In such sm all systems it was found to be excessively cost inhibitive to utilize horizontally placed grow troughs down the sides of the a-frame; instead it was found that vertically arranged troughs would be as functional with a lower construction cost and greater ease of maintenance. 81

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Grow Mediums T he selection of grow medium is es sential in the design stage of any modern hydroponic system, save for aeroponics systems which utilize no grow medium. Aside from aeroponics, all modern hydroponic systems utilize some type of inorganic rooting medium. Rockwool and stonewool are different variations of the same commonly used rooting medium, made by the extrusion of molten rock at extremely high temperatures into a ma terial much like fiberglass. This material is commonly sold pressed into block, mat, slab, and cube form. Clean and non-toxic Rockwool and stonewool feature a high water holding capacity, provide good aeration, and are nonreactive width nutrient solutions. Both materials provide a sound germination environment and ideal long-term gr owth medium, negating the need for seedling transplant. The only negati ve of Rockwool and stonewool use is on the behalf of the user, who may ex perience slight skin irritation from contact. Vermiculite, a naturally occurring mineral that expands with the application of heat, is a porous, spon gelike, sterile material popular in hydroponic systems. It's high water absorption capacity, five times its own weight, is utilized extensively in eb b and flow hydroponic systems (Resh, 2004). 82

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P erlite, like vermiculite, is natura lly occurring, it is an amorphous volcanic glass with a relatively hi gh water content. When sufficiently heated, it has the unusual property of greatly expanding. It makes a good germination medium on its own as well as when mixed with vermiculite. Ordinary gravel, ranging in size from five to 15 mm in diameter, make an excellent grow medium for al ready sprouted plants. Prior to use the gravel must be leached and sterilized. Depending on system design a high weight density of gravel may or may not be an advantage. Common sand, rock grains varying in si ze from 0.6 to 2.5 millimeters, makes a superb and inexpensive grow ing medium. Most sand, however, is heavily contaminated and must be thoroughly leached and sterilized before initial use. Sand exhibits a low water holding capacity, a high weight density, and almost no reactivity to nutri ent solutions. In many systems, it is adequate for both germination and plant grow out. Plant selection for systems Selection of plants for a hydroponic system must be based on system design. Not all species of plants will thrive in all hydroponic systems. As well, not all plants will survive in the local climactic environment of the system; this can, however, be re medied by the construction of a greenhouse to control the environment bu t will result in a greatly increase 83

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system cost. Lighting, as previously note d, also plays a crucial role in plant selection as not all plants will survive, much less thrive, if grown under artificial lighting. Thus, if artificial li ghting is used, plants must be carefully selected, as in the selection of only green leafy vegetables and non flowering plants for use under fluorescent lighting conditions. Plant spacing must also be taken into cons ideration, in smaller systems it may be more advantageous to select species which can be grown relatively closely together to increase producti on rather than species require more individual space. Plants Lettuce Lactuca sativa Figure 22 Lettuce (Nelson, 1998) 84

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I n aquaponic and hydroponic systems there is no group of plants more commonly grown than lettuce. Most common varieties of lettuce thrive in aquaponic systems. Most le ttuce varieties also mature extremely rapidly, some varieties in as few as 40 days from initial planting (Nelson, 1998). Of some note, however, is th at iceberg lettuce is not ideal for hydroponic production due to its long, 90 day, grow period (Nelson, 1998). Lettuce can be successfully grown in nearly every form of hydroponic grow system. In general, most variet ies of lettuce will grow well between 60 to 80 Fahrenheit. The nutrient solution fed to lettuce plants should have a pH of between 5.8 and 7.0 (Nelson, 1998). Preparation for market is extremely simple for most varieties of lettuce, the heads are generally either harvested whole, or leaves of some species are harvested periodically, allowing for continued production from a single plant. Of some note, however, is the growing ma rket for entire, live, heads of Bibb butterhead lettuce, with roots intact The heads are harvested whole, most commonly from hydroponic grow facilities, washed, packaged in a suitable container, and shipped to ma rket, where they will thrive for a surprising period of time. Arugula Eruca Sativa 85

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Figure 23 Arugula Arugula, also known as rocket, is in edible plant native to the Mediterranean region. An annual plant, arugula will grow to nearly 30 inches tall. From germination arugula typically requires 40 days to reach maturity. Commercially arugula has only been cultivated since the 1990s, however, evidence of intentional cultivation dates back to Roman times. Arugula is best seated in its final grow container as it is sensitive to transp lant shock. It will perform best in a temperature range of 40 to 55 F (Resh, 2004). Arugula prefers moist soil conditions. Therefore, in a hydroponic system the grow media must possess adequate water retention capabilities. Arugula is well suited to ebb and flow hy droponic systems, where regular seedings and harvesting can take place allowing for continuous production. Arugula plants will provide for long-term continual 86

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har vest as long as leaves are ha rvested before the plant reaches maturity. Collards Brassica oleracea Figure 24 Collards Collards, an open leafed, non-head forming, member of the cabbage family, are extremely easy to grow (Resh, 2004). Colladrs prefer well drained substrate and highlight cond itions. Germinatio n occurs in as few as four days with the plant reachi ng maturity within 55. Collards will thrive in an extreme range of temperatures, efficiently growing from 40 to 85F. In hydroponic systems the nutrient solution pH should be between 6.0 and 7.5. Of particular note in the farming of collards, dry root 87

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cond itions lead to more bitter tasting leaves, making them prime candidates for hydroponic production. Basil Ocium Figure 25 Basil (Nelson, 1997) A member of the mint family, it is considered an annual, but with regular cuttings, it can produce constantly for months. Basil requires considerable light, and grows to a heig ht of 12 to 18 inches (Nelson, 1997). Study in hydroponic and aquaponic sy stems has shown basil to grow best in NFT channel systems as its root syst em is sensitive to excessive moisture, supported by Rockwool cubes (Nelson, 1997). Basil seeds will germinate in 4-7 days under optimum conditions. Sensitive to cold temperatures, basil is best grown in closed environments. Basil is easily propagated from cuttings, therefore once established in a system, further seedings are 88

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unnecessary. Har vesting basil involves trimming complete stalks, just above the lower sets of leaves, allo wing for later regrowth and further harvest. Dill Anethum graveolens Figure 26 Dill 89

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Di ll, a short-lived perennial herb, is the sole species of the genus Anethum Under ideal conditions dill will gr ow to a height of 24 inches. Dill will thrive in temperatures below 75F and requires full light (Cancio-Bello, 1999). In hydroponic systems dill has been found to be able to continually produce when harvested only as cuttin gs and grown in Rockwool cubes. After a seven-day germination period a first harvest may be taken in approximately 4 weeks under optimum co nditions. A hardy plant, dill is susceptible, however, to fluctuations in nitrogen, and therefore a constant supply must be provided by the nutrient solution. Chives Allium schoenoprasum 90

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Figure 27 Chives (Nelson, 1999) Chives, a member of the on anio n family, thrive in aquaponic systems. A beneficial pl ant, chives have been known to inhibit certain insect infestations within grow system s (Nelson, 1999). Chive seeds must be sown directly into a growing medi um within the system; perlite or Rockwool is a preferred substrate. Ch ives will spread throughout a system by way of root propagation; therefore, they must be isolated if grown with other species. Depending on the variety, chives will grow to a height of 8 to 14 inches. Continued production can be achieved through frequent cuttings, as often as every four weeks (Nelson, 1998). Chives are harvested simply by cutting each stock at it s base, washing, and packaging as desired. Chives grow well in temp eratures that range from 60 to 80 91

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Fahrenheit. Best growth wi ll be achieved if the nutrient solution has a pH value six to seven (Nelson, 1999). Watercress Nasturtium officinale Figure 28 Watercress (Nelson, 1998) Watercress, as it name implies, is a hydrophilic plant and one ideally suited to the aquaponic and hydrop onic grow environment. Watercress can be easily grown from seed, pr opagated from cuttings, or even allowed to reseed itself within a system. Watercress will grow well under all light conditions and grows rapidly when seeded into a well suited system, exhibiting strong growth in slightly al kaline environments. Best growth will be achieved when the nutrient soluti on has a pH value of 5.8 to 6.5 92

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(Nelson, 1998). Watercress is harves ted by cutting just above the root mass or earlier growth, harvested as sprouts. Mint Lamiaceae Figure 29 Mint (Nelson, 1998) The most vigorous of all perennial herbs, it grows very well hydroponically and is tolerant to low light levels. Mint is a perennial herb propagated by root division. It is easy to grow, develops rapidly, prefers a moist root environment, and thrives in most light conditions. The types of mint most commonly grown are peppermint, pennyroyal crinkle leafed spearmint, spearmint, and applemin t. There are, however, over 600 varieties of mint (Nelson, 1998). Thes e are normally classified by their 93

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essential oils, the two main cate gories being menthol containing peppermints and the scented spearmints Mints preference for moist root conditions and a neutral pH make it an ideal group for aquaponic production. However, due to its aggressi ve nature in propagation it should be kept in individual or isolated grow beds in order to not crowd out other species. Mint favors regular cuttings, which encourage continued growth, and to serve as harvest times. The plants will thrive in temperatures ranging from 60-70 OF. As growth slows the mint plants should be replaced within the system. The most common pe sts to mint plants are aphids and mites. The roots of more vigorous pl ants may need to be trimmed when in NFT systems to prevent clogging of the raceways. (Nelson, 1998) Microgreens Microgreens are a relatively new product in the field of hydroponic crop production systems. Microgreens are actually just very young plants of most normally grown species, not sprouts, with which they are commonly confused. Generally, microgreens are larger than sprouts and have developed to the point of producing their first set of adult leaves. In some production systems the harves t point of microgreens is when an average height, generally 2 to 3 in ches, has been attained (Morgan, 2008). They are planted and allowed to only partially develop beyond 94

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sprouti ng before harvesting, most co mmonly within 14 days of seeding. They are considered to be more benef icial in nutrients, and according to many chefs have a much more robust flavor and have become a growing trend on the upscale green cuisine movement (Morgan, 2008). Microgreens are among the easiest to grow crops for any hydroponic or aquaponic system. Th ey require little or no planting medium and can be ready for harvest in as little as two weeks. For the small scale gardener looking to primarily supplement household greens they are a great, albeit, slightly la bor intensive crop choice, due to the frequency of seeding and harvest, wh ich in some instances may serve as more pleasing interactive activity for the small scale producer, rather than a more intermittent interaction with lo nger term grow out systems. They do have an added advantage in systems comprising multiple growth phases, for as they grow, they can also be transplanted and grown out to mature plants in other regions of the system. Many plants commonly grow n in hydroponic systems can successfully be grown as microgreens, provided that they are harvested just as they begin to form adult leav es. The harvest of most species can be facilitated by using a granular growth medium, which can be washed or flooded away from the roots. While consuming the entire plant, roots and all, may, to some, seem primitive, the roots in younger plants commonly 95

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carry wi th them a greater density of flavor and nutrients than the young leaves. Depending on the demands of the consumer, microgreens may be harvested by cutting just above the root level. The most notable example of mi crogreen production is that of wheat grass, which, over the course of the last decade, has become a marketplace staple. The trend to wards microgreens, originating in California, has spread worldwide and microgreen products are in marketplaces globally (Morgan, 2008). Just as rapidly as the interest in microgreens has grown, the diversification of microgreen production systems has occurred. The vast variety of equipment and system designs used in microgreen production are all linked through one extreme boon to the cropper; microgreens are best grown under extremely dense conditions. Through dense seeding, not only is production per area drastically increased, but the resulting plants will grow more tall and straight than if sprouted in a less confined environm ent. Seeds intended for microgreen germination may be sprouted directly in the grow environment, however species which exhibit mucilaginous seeds are best presoaked, and only once their moisture retaining layer has formed, should they be sown onto the surface of the grow medium. In addition, due to their short growth cycle, more powerful, high-intensity discharge lighting fixtures are not 96

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requi red to promote productive growth. Instead, less expensive fluorescent fixtures are perfectly suitable (Morgan, 2008). Depending on system design, irriga tion over the grow beds may be facilitated by many means. Capillary matting, ebb and flow systems, and direct mist systems have all prov en effective in th e germination and production of microgreens. Many sy stems are simply mo dified existing hydroponic grow facilities, modified to enhance the production of the smaller greens. In large-scale NFT microgreen production systems, the standard narrow gauge NFT troughs ar e replaced with much more broad tray style sluice ways in order to increase grow surface area (Morgan, 2008). In commercial water culture system s float or raft systems have given way to multi-tiered tray grow systems with multiple levels of large grow beds staked vertically allowing only enough space between beds to allow for natural light to enter or prov ide space for artificial lighting at each level. In many of these tiered sy stems, each tier column acts as its own progressive grow system, with fres hly sown grow trays inserted at the bottom on the lowest level, only to be raised with each progressive day or two (Morgan, 2008). This progressive system reduces costs on the overall grow scheme as prior to germination the seeds require no light, only moisture. In small scale systems, shallow nursery trays are often utilized as grow beds. 97

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Mi crogreen growers have utilized the same growth medium materials as hydroponic croppers wi th numerous additions due to their shortened exposure to the grow environment. Innovative materials often utilized by microgreen producers incl ude burlap sheets, paper towels, and recycled cloth (Morgan, 2008). Although most grow mediums are effective for microgreen production, sand must be noted as problematic in certain cases due to its propensit y to contaminate the final product with grit particles. The progressive nature of microg reen production systems, paired with their high production density ma ke it feasible for on-site microgreen production at the location of utiliz ation in many cases. Being highly productive per unit of area, microgr eens could conceivably be viable for indoor house hold growers or individu als looking to make a profit through the modification of warehouse space, ga rages, or other enclosed areas. Microgreens, unlike sprouts, re quire nutrient supplementation in order to grow to a harvestable size. Their nutrient requirements however are markedly lower than those of plants intended for grow out. Therefore, a much greater volume of microg reen biomass may be produced per given unit of nutrient supplied than with larger more traditional crops. In an aquaponic system this would result in either a fewer number of fish 98

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bei ng needed to supply the nutrient for a given size grow bed, or a larger grow bed being supported by the same number of fish. 99

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Aquaponics Aquaponics is the commensal growing of both aquatic animals and plants in a closed recirculating environment. In an aquaponic system the effluent of the aquatic animals accumulates in the water in which they are grown and is utilized by the plants in the system as their primary source of nutrient. In return, the plants reduce or eliminate the toxic wastes in the system; cleansing t he water for the aquatic animals. In an aquacultural environm ent, culture species effluent accumulates as a byproduct of respiration, and would continue to the point of toxicity, unless removed through a filtration system. This waste is extremely high in nutrient howeve r, and processable by the culture species. Within a biofilter, organisms utilize the nutrient rich effluence as a source of sustenance, eliminating it from the system. In a hydroponic system, a liquefied nutrient solution is utilized to more efficiently deliver needed nutrients to growing plants. Aquaponics systems are a meshing of these two fields. The aquacultural system acts as the nutrient solution provider for the hydroponic system through the creation of effluent, and nutrient rich water. The hydroponic system acts as the biofiltration unit for the aquacultural system by cleansin g the water of its effluence thus 100

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maintaining hab itable culture condit ions for the organisms contained within. The origins of aquaponic systems date back thousands of years. Among the most cited examples of early aquaponic farming methods is the accidental introduction of fish into flooded rice paddies in the Far East, as previously mentioned (Nelson, 1998). The fish would protect the flooded paddies from waterborne pests and provide nutrient to the plants. As the process of flooding rice patties progressed, the farmers would have adapted to increase their harvested yield of fish. At the end of the planting season, the fish, which had increa sed in size over the period, and the plants, would be harvested. The plants would be prepared for human consumption, and the fish would either be consumed or reutilized in other fields until of consumable size. In more modern times, aquaponics has experienced a reemergence in both commercial and domestic growing operations. Commercially, many fish farming operations, realizing the potential from the wastes they produced, and were fo rced to mitigate at considerable cost, saw aquaponics as a potential source of increased revenue both from the reduced filtration and waste disposal costs that would result and from the profit of the produce they could grow. Additionally, hydroponic croppers, recognized the growing global trend towards increased 101

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seafood cost, expanding rates of consumption and market value growth in aquatic organisms. To their benef it, they found a possible source of increased revenue with a minimum of investment. Through an addition of an aquacultural unit to their systems they would be able to negate their dependence on fabricated nutrient solutions, modifying their systems to still include a single input, feed, with the result of dual outputs of fish and harvestable produce. The benefits of reduced nutrient, land, and water usage were lost on neither field of producer, and research was quickly begun into more modern integrated agricultural systems. Of key design into commercial aqua ponics systems is the ratio of fish feed input to plant grow bed size. If accurately fed, the quantity of feed provided to the fish will result in a calculable quantity of nutrient supplied to the plants in the form of effluent. Early research at the University of the Virgin Islands Agri cultural Experiment Station utilized hydroponic raft culture in an outdoor environment, with the fish housed in circular pools. Over a 16 year st udy in the system, the optimum ratio found for production of the leaf lettuce was 57 g of feed per square meter of grow bed space per day (Rakocy, et al., 1997). It was found that the system was capable of supporting a feeding rate of up to 180 g of feed per cubic meter of actively grow ing lettuce beds per day. It was discovered, however, that solids filtration was still essential to the effective maintenance of water quality. Lacking a solids removal system, the solids 102

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would accumulate on plant roots crea ting an aerobic stones and blocking the flow of water and nutrients to the plants. Initial experimentation into commercial scale production trials began at the Agricultural Experiment St ation in 1995. The focus of the trial was the production of red tilapia and hydroponic leaf lettuce in an outdoor setting. The production unit co nsisted of four circular fish rearing tanks, each 4.5 m in size, and six 11.5 m hydroponic tanks measuring 29.6 m long by 1.3 m wide by 8.4 m deep, with a surface area of 214 m (Rakocy, et al., 1997). The system was plumbed to providing maximum flow rate of 170 L per minute and an av erage retention time of 1.7 hours in the fish tanks. The rearing tanks were aerated utilizing mechanically force diffused air. Production of tilapia was staggered so that one of the six tanks would be harvested every six w eeks. Initial stocking rates of 222 mixed sex fingerlings per cubic meter were reduced to 178 male fingerlings per cubic meter, for a total stocking of, at maximum capacity, 3204 individuals, or 801 per rearing tank. The hydroponic grow beds were constructed of floating polystyrene sheets supporting the net pots. Pr oduction in the grow beds was staggered so that it one fourth of the lettuce was harvested at a marketable size of 252 650 g every week, after a four-week grow out period. Three week old transplants we re utilized to populate the system. 103

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Production over seven harves ts, taking place during a 42 week period, resulted in average harvest weight of 345 kg, equivalent to it an annual total production of 170 kg per cubic meter of rearing tank area. Average size attained by t he tilapia was 520 g at the time of harvest, with an average growth rate of 2.9 g per day, and a 1.76 feed to body mass ratio, as well as a surviv al rate varying from 78.6 to 97%. Mortality was concluded to have result ed from bird predation, disease, hurricane damage, and power failur e (Rakocy, et al., 1997). Over the course of 90 harvests, ma rketable production averaged 26 cases per harvest, with 24 to 30 heads per case. Production of leaf lettuce resulted in average crop of 78.5 kg per cubic meter of rearing tank space. Losses within the hydrop onic unit occurred due to caterpillar damage, wind damage, tip burn, r oot disease, and root damage resulting from ostracods (Rakocy, et al., 1997). The system was shown to maintain good water quality throughout the life of the experiment, with a water consumption rate of 1.6% of t he system volume per day (Rakocy, et al., 1997). Research conducted at Inslee Fish Farm in south-central Oklahoma was based on an already existing 24, 000 gallon rectangular tank 20' x 40' x 5', separated by caging to allow for sequentiation of production. The tank was known to have a potential output capacity of 1000 pounds of 104

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ti lapia per week. Aeration within the tank was provided by a 5 hp motor, which also served as an airlift to feed water to the grow beds. A 30' x 100' greenhouse was constructed to house the grow beds. 16 grow beds measuring 4' x 12' and 17 grow beds measuring 4' x 14' were constructed and prepared as NFT beds, without a grow medium, for a total grow area of 1720 ft.. The system was designed so that after traveling through 100 feet of grow beds, the water would be returned to the fish rearing tank. Flow rates were regulated to ensure that all of the tank's water would cycle through a grow bed 2.2 times a day. Chives were selected to populate the hydroponic portion of the system (Nelson, 1998). During trials, it was found that the size of the grow bed was not sufficient for the maximum stocking density of the rearing tank, which at maximum capacity could hold 48,000 pounds of fish. Calculations showed that the grow bed area would need to be quadrupled to effectively manage the effluence produc ed by such a stocking level. The hydroponic production of the system was staggered, allowing for a one quarter total harvest, of 100 to 120 poun ds of Chives, every week. Chives, unlike most other crops, do not need to be reseeded into the system, instead only thinned periodically as t hey self propagate. The production of Chives in the system was found to be more profitable than the fish produced. If operated at maximum capacity, with expanded grow beds, 105

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the system would be capable of gros sin g over $150,000 per year (Nelson, 1998). Research into the benefits of aq uaponics has not been limited to commercial scale operations. Extensive research has been conducted in all walks of small scale aquaponics wi th varied intentio ns and designs. While not typically studied scientifically, the results garnered by the trials of the systems may provide a pathway to more productive aquaponics systems both on the domestic and commercial scale. One such aquaponic system was de signed by Warner Daniels III, the major objective of his system was to test the effectiveness of scrounged, salvaged, or discarded components in reducing household dependency on the market purchased produce through domestically produced vegetables. The aquaponi cs system desig ned by Daniels consisted of a fish rearing tank constructed out of a discarded 45 gallon storage box, a settling tank made from a 32 gallon plastic trash can, a grow tray made from a 32 quart plas tic tray, scrap PVC for planting, and a purchased 250 gallon per hour pump The grow medium he selected was a commercially available expanded clay medium and Rockwool cubes, which he purchased from a loca l supplier. Irrigation to the grow bed was provided from purchased drip emitters (Daniels, 1997). 106

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Figure 30 Warner Daniels' NFT trough grow system featuring gravity assisted particulate removal and grow bed draining constructed from primarily recycled components Once assembled, as diagrammed in figure 30, the system was filled to capacity with water and allowed to rest for a 24 hour period before the introduction of nitrifying bacteria. After a two day establishing period, the water was tested and found to have a pH of 7 and a dissolved oxygen content of 6 to 8 mg per liter, based on water flow rates. Due to their local abundance, Daniels elected to stock the tank with gold fish, which were to be fed a unrecorded amount of or dinary flake fish feed on a daily basis. Into this settling tank he es tablished three small water hyacinths to aid in the removal of particulate matter. The expanded clay and Rockwool cubes were leveled in the grow bed and seeded with butter lettuce seeds (Daniels, 1997). Within one week, sprouting had proceded and the seedlings had reached microgreen size. The less vigorous seedlings were thinned out at this point. Over the next several w eeks, both the water hyacinths and the lettuce seedlings showed significan t growth. The hyacinths grew so 107

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rap idly that Daniels was forced to thin them as well. After three weeks the lettuce had reached a point near harvest. However, due to circumstances beyond the experiment er's control, marauding animals destroyed the crop. Although no numerical data was extrapolated from this trial, it can be deemed a success. Although inco mplete, the system proved capable of producing lettuce to near maturity, successfully produced water hyacinths, and provided a stable growth system for goldfish. Likely the system would be capable of complete lettuce production, and could have served as a grow out system to raise fingerling Koi to a more profitable size. It was also proven to be a viable means of small-scale hyacinth production from the result s they can be deduced that such a system could be effective in the pr oduction of microgreens as well. In another reduced size trial, a small scale ebb and flow aquaponic system was designed, constructed, an d operated by Peter Thiesen. The system deconstructed consisted of a 40 gallon Fish grow out tank constructed from a recycled barrel, a 2' x 2' grow bed filled with sterilized pea sized gravel, and a pump timed fo r 15 minute flood and drain cycles. During the flood cycle water depth was controlled to remain at 1/2" below the upper level of the pea gravel through the use of overflow ports. This feature was intended to reduce algal growth in the grow bed. The 108

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grow bed was posi tioned off to the side of the rearing tank and plumbed to create a rotary water current within the rearing tank as water returned from the grow beds. This was done to facilitate sediment movement within the tank in the hopes of having it relocated to the grow bed. A 250 W high-intensity discharge metal hali de lamp, providing 1002 2500 lm was utilized to provide light to the grow be d. The fish rearing tank was stocked with 60 fingerling tilapia, feed type and feed quantities were not recorded (Theisen, 1997). Over the course of the systems op eration it successfully produced radishes, onions, lettuce, beets, br occoli, and spinach. Throughout the trials issues with water return and over flow ports clogging due to root mass growth were recorded. These issues can be attributed to the lack of mechanical solids removal resulting in more extensive root development. During trials, fish growth was continual however their behavior was observed to be sluggish. Testing found dissolved oxygen levels to be below 3 ppm, which was rectified by the addition of a small mechanical aeration unit. Over the course of several trials the fish were found to have grown to an average weight of one quarter pound. Due to the stocking density of the rearing tank, necessary feed levels to sustain the fish exceeded the bioremediation capabi lities of the grow bed and an 80 gallon sponge filter was added to the system. This was rapidly removed due to excessive maintenance requir ements and replaced with a simple 109

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foam frac tionator. The foam fractionator produced 1 gallon of removed effluents and floatable waste per day. This removed waste was collected and utilized, effectively, to fertilize plants outside of the system. While growing lettuces the system was ca pable of supplying enough produce to satiate a familys need two to five days per week (Theisen, 1997). While no hard numerical data were retrieved from the system, it was proven to productively produce fish and vegetables, along with fertilizer. With this system, grow bed size could be increased, potentially increasing the vegetative output of the system to a level where the user would no longer be dependent on purchased gr eens. The system also established that small-scale aquaponics systems could be effectively operated under artificial illumination. Advantages/disadvantages to aquaponics There are numerous distinct advantages and disadvantages to hydroponic cropping. In most instances, the water within an aquaponic system is reutilized, reducing waste and cost to the producers. For many the aesthetics of organic fertilization on their crops is very attractive and as the plants are fertilized wholly by the fish they can be considered organically grown. In recent times, intensive fish culture has come under criticism for water borne waste produc tion; aquaponics nearly eliminates the output of such effluent. As t he popularity of locally grown crops 110

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i ncreases, aquaponic units of relati vely small scale can be constructed near areas of demand, providing the benefit to the consumer of local growth and reduced transportation costs to the grower, meanwhile filling the demands of the rapidly growing market. However, aquaponics does present many disadvantages as well. Due to the relative complexity of the systems and the components required to build them, it is relatively high in cost to initiate aquaponic cropping. Due to the numerous po ssible arrangements of system components, much of the research in to aquaponics, and previous system trials, cannot be utilized unless as an exact replication the original experimenters research, which in ma ny cases in neither feasible nor desirable. This is due to special and environmental constraints on the systems. Most commercial system s are an amalgamation of many different concepts as best fits the in dividual systems requirements. Due to the relative complexity of many aq uaponics systems the energy cost of operation can be quite high. In a ccordance, the complexity of all aquaponic systems may result in many more opportunities for failure; e.g. failures such as grow bed leaks resu lting in the fish containment tank being pumped dry, therein a complete loss of the fish stock. Notes on potential on culture species 111

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T here are numerous factors affecting the aquaponic growers decisions of which species to utilize. Naturally the first measure to consider when selecting species is climate, even if growing indoors. Different species of fish and plants have different temperature requirements and not all are suitable for each other. System size is also critical when selecting the fish for an aquaponic system. Different fish have different requirements for containment system size. There is however, no exact rule to be followed. Factors such as fl ow rate, tank shape, temperature, oxygen to be supplied, grow bed size and planned stocking density all interact and play a role in decisions regarding which species to be included in the system. Plants as well have many factor s to consider before planting. Depending on the tanks size and feeding rate, the quantity and species of plant may need to be adjusted. For example, large fruiting plants will not be able to be planted as densely as heads of lettuce due to both special constraints and the nutritional requirements of the plants (Jones Jr, 2005). Also certain species of plants are not suitable for moist growing conditions and although it may be possible to grow them under carefully controlled aquaponic conditions it ma y not be economically feasible to do so. 112

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Methods Materials used in study See append ix A Clarification and definition of components See appendix B Fish populating the system Crayfish A population of six cray fish, captured locally. Channel Catfish Ictalurus punctatus Four small Channel catfish, captured locally. Figure 31 Locally captured Channel catfish utilized in the research system Tilapia 113

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T wo small Blue Tilapia, captured locally. Figure 32 Locally captured Blue tilapia utilized in the trial system Mosquito fish 114

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Approxi mately 75 Mosquito fish, captured locally. Figure 33 Population of locally captured Mosquitofish populating the test system Plants Tested in the System Table 8: Plants tested in system Arugula Eruca sativa Basil, Sweet Ocimum basilicum Chives Allium schoenoprasum Collards, Georgia Southern Brassica oleracea Dill, Mammoth Anethum graveolens India Mustard, Florida Broad Leaf Brassica juncea subsp. India Mustard, Southern Giant Curled Brassica juncea subsp. Kale, Dwarf Blue Curled Brassica oleracea Lettuce, Black Seeded Simpson Lactuca sativa subsp. Lettuce, Burpee Bibb Butterhead Lactuca sativa subsp. 115

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Lettuce, Iceberg A Lactuca sativa subsp. Lettuce, Parris Island Cos (Romaine) Lactuca sativa subsp. Lettuce, Salad Bowl Lactuca sativa subsp. Mesclun, an assortment of: Endive, green curled Kale, red Russian Lettuce, red romaine Lettuce, paris island cos Lettuce, salad bowl Lettuce, lolla russa Mint, Spearmint Mentha spicata Radish, Cherry Belle Raphanus sativus Spinach, Teton Hybrid Spinacia oleracea System size and spacing constraints The design protocol allotted the use of no more than 128 ft. of space. This allotment stip ulated that no more than sixteen square feet of floor space, and no more than eight vertical feet to be occupied by the system. This was deemed to be a re asonable allowance of indoor space in the domestic setting. How materials were prepared prior to construction 4 pvc wastewater pipes 116

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T he 4 pvc wastewater pipes were cut to a length of 50 using a radial arm saw. Then using the same saw, the lengths were ripped longitudinally into equal halves. The sections were then scrubbed and washed in fresh water to remove contaminants. 4 pvc water pipe The 4 pvc water pipe was cut into tw o 48 inch lengths using a radial arm saw. The two lengths were then ripped lo ngitudinally into equal halves on the same saw. The sections were then scrubbed and washed in fresh water. 2 pvc water pipe The 2 pvc water pipe was cut to a l ength of 48 with a radial arm saw. Then, ten opposing 1/4 holes were drilled every four inches and three opposing holes were drilled at thirds of the pipes length the holes were then threaded with a tap. The pipe was then scrubbed inside and out and washed with fresh water. Into each hole was screwed a brass plated valve, with the threads wrapped in Teflon tape, until snug, with all spigots oriented to the same perpen dicular from the 2 pipe. 2x4x8 lumber, not pressure treated The 2x4x8 lumber was cut to four l engths of exactly 8 and five lengths of 48 using a radial arm saw. The lengths were then sanded to remove 117

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rough edges and spl inters. The lengths were then painted with two coats of all weather deck paint to prev ent rot and possible contamination through leaching. Insulation sheets The 4x8 insulation sheets were cut to a length of 50. The sheets were then cut into strips 4 wide on a ba nd saw. Each strip was then drilled every 4 along its length with a 2 hole saw. For half of the strips the initial hole was drilled 4 from the end of the strip, the remainder were initially drilled at 6 from the end of the strip. This was intended to allow a more staggered planting arrangement in the grow troughs. 65 gallon rectangular tanks The tubs were scrubbed with a bleach solution and then thoroughly rinsed with fresh water. All PVC and caps, bushings adapters, and fittings All PVC hardware was thoroughly scrubbed and rinsed in fresh water. Fluorescent light fixtures The light fixtures were assembled as per the instructions included with them. The bulbs were not installed until the end of construction. Plastic storage tubs 118

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U sing a high speed rotary cutting tool the tubs were cut to a depth of three inches. Using a heated nail, four holes were melted into one of the short edges of each tub, ensuring that the holes were no greater than 3/16. Fine grade polyester filter material The 1" x 36" x 6' section of fine grade polyester filter material was cut into sheets, using scissors, to fit into the bottom of each plastic storage tub. Net Pots The net pots were prepared by cutting their bases out to allow the rockwool cube to extend beyond, ye t be firmly held, when inserted. Construction of system Construction of the system began wi th the assembly of the A-frame. Two lengths of 2x4 were inserted into each of the two sawhorse brackets, forming the legs of two A-frames. Then, with the help of assistants, the legs were raised and brought together on each of the two brackets. A 2x4x48 crosspiece was then inserted at its ends into the appropriate cross-member slot in both of the sawhorse brackets. 119

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Figure 34 Sawhorse bracket with legs and 48" cross piece inserted, situated in research location, secured with deck screws The legs of the A-frame were then spread to a distance of 48 between each foot of the A-frame. T he selected site location was then prepared. Due to laboratory space constraints the system was constructed in a sheltered area underneath the lab. The site was leveled and the a-frame placed over it. Deck screws were then installed through the brackets and legs to ensure frame stability as shown in figure 34. Two lengths of 2x4 were then installed, with deck screws, horizontally at a height of 30 at each end of the A-frame, with the cross pieces extended seven inches beyo nd each leg. T he two remaining 120

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p ieces of 2x4 were then affixed with deck screws to the cross pieces previously installed, forming a shelf, shown in figure 35. Figure 35 The base of the A-fram with the cross-members installed and 2x4" shelves installed The two lengths of 4PVC water pipe were then placed on the shelf formed on the exterior of the A-frame with 2 of pipe extending beyond each end of the shelf. The pipes were affixed to the shelf using silicone. Using PVC cement, the two pipes were then capped with pipe ends, see figure 36. 121

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Figure 36 4" water return trough installed on 2x4"shelf capped with a full sized 4" end cap Then at the center point of the two pipes an inward facing hole was drilled and tapped. Through these holes threaded PVC fittings, wrapped in Teflon tape, were inserted, forming an outflow for the water return troughs positioned as shown in figure 27. 122

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Figure 37 4" water return trough featuring 1" water return port Next the twenty waste water pipe halves were set onto the A-frame with each having one end resting in the horizontal trough, the other on the A-frames uppermost crosspiece. Ten vertical pipes were set on each side of the A-Frame, figure 38. 123

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Figure 38 Completed a-frame during installation of vertical NFT grow channels into 4"water return trough and along the upper beam of the a-frame. Also depicted is the layout of the microgreen grow area situated internally on the a-frame The two 65 gallon tanks were then arranged lengthwise beneath the A-frame. Figure 39 Fish grow out tanks, situated beneath the microgreen grow section of the system, connected with and auto siphon made with excess pvc from construction 124

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T he 5 section of 1 vinyl tubing was friction fitted to the Mag-5 pump, the other end was then fitted to a male threaded 1 pvc fitting. The whole pump assembly was then plac e inside of the filter bag, as shown in figure 40. Figure 40 Assembled and installed pump and filter bag components installed in system Then, using pvc cement, one end of the 2 distribution pipe was sealed with a pipe cap. To the other end of the distribution pipe a pvc three way fitting was glued and sealed with only one perpendicular hole left open and aligned in the same dire ction as the spigots. Into this 125

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hole a 2 male to female 1 threaded fi tting was glued, shown assembled in figure 41. Figure 41 Assembled water distribution inlet Two slices of scrap pipe from the cutting of the water return troughs were then affixed, using deck screws, along the top of the upper beam of the A-frame, to form holding trough for the water distribution pipe, positioned as in figure 42. 126

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Figure 42 Upper beam of grow frame featuring installed PVC distribution pipe retainer The threaded male fitting on the 1 vinyl tubing was then wrapped with Teflon tape and screwed into the female fitting on the water distribution pipe. 127

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Figure 43 Water distribution pipe installed and connected to water pump with vinyl tubing The distribution pipe was then set in its respective trough on the top of the A-frame with the fittings aligned downwards, as in figure 44. Figure 44 Arrangement of grow bed nutrient solution distribution tubes emanating from primary water distribution pipe 128

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Onto the 20 fi ttings spaced at 4 c enters a four inch section of 3/16 airline tubing was attached and position ed to be touching, at its free tip, the vertical trough directly below it when they were installed. To the remaining six fittings, four foot lengths of 3/16 airline tubing were attached and positioned to be threaded between the top ends of the nearest vertical troughs and allowed to hang freely within the center of the A-frame, set as in figure 45. Figure 45 Nutrient solution distribution tubes positioned to supply grow zones Next, the electrical components of the system were assembled and installed. Above each water return trough, one fluorescent light fixture was attached to the ceiling using deck screws and suspended using the hardware supplied with the lights. The fixtures were suspended at a height 129

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of 6 and angled to wards the grow troughs at an angle of approximately 60O. The remaining light fixture was installed to the lower side of the upper cross member within the A-frame, as shown in figure 46. Figure 46 Assembled grow system with exterior lighting installed and angled to evenly distribute light over exterior grow zones All fixtures were installed with th eir electrical cords aligned to the end of the A-frame where the pump was located. Then, to the end of one leg of t he A-frame on the pump side, the 3way outlet splitter was affixed, serving as the electrical input point for the system. To this the pump was plugged in and the electrical timer was attached. To the timer the power stri p was attached and into the power strip the light fixtures were plugged in. 130

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Figure 47 Installed and connected electrical distribution and timing system for grow system Within the A-frame, the scrap pvc from cutting the water return troughs was cut to 48 and laid, formin g a stable platform. Then, into each hole melted into the Rubbermaid tubs, a six inch length of 3/16 airline tubing was pressure fitted, with approx imately five inches of tubing left hanging beneath the tubs to serve as water level control and return points. 131

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T he tubs were then positioned on the platform within the A-frame, positioning the exposed tubing thro ugh the platform adjacent to the water return trough. Into each tub, a cut mat of filter material was fitted. Figure 48 Installed and prepared microgreen grow containers situated in the interior of the a-frame The strips of foam insulation sh eeting were then prepared. Using a two inch hole saw, twelve holes were cut into each strip at 4 centers. On ten of the strips the initial hole was st arted 2 from the end of the strip, on the other ten the initial hole was drilled at 4, as in figure 49. 132

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Figure 49 Foam insulation strip, drilled and prepared for installation in system and insertion of net grow pots This discrepancy allowed for the st aggering of planting positions between grow-troughs. The foam strips were then pressure fitted into the grow troughs, alternating between the two strip types by hole positions. The Rockwool cubes and prepared net pots were th en assembled, as in figure 51. 133

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Figure 50 Prepared net pot and Rockwool cube prior to assembly Figure 51 Assembled Net pot and Rockwool cube, ready for insertion into system Into each hole a 2 net pot was pr essure fitted, ensuring each pot was pressed into each trough and that the Rockwool cube touched the trough below. 134

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Figure 52 Assembled net pot and rockwool cube, inserted into the insulation board grow bed of a channel within the NFT portion of the system The grow troughs were then positi oned in the water return troughs 135

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Research protocol How measurements were made and what calculations were preformed Measurements made on the system included water qual ity and measurements and biomass produced. The cost of system inputs and value of system outputs was also calculated. Water Quality Water quality was measured weekly using a standard aquarium style test kit. While the water conditions were allowed to slightly fluctuate, pH was to be maintained at approx imately 7.6. The planned procedure for any large fluctuations in wate r quality was a 20% water change; however, over the course of the experiment, this was not necessary. Feeding protocol The feeding protocol established fo r the system was 1 ounce of 40% protein, floating, processed pelletized fish feed 1/8 to 3/16" in diameter, fed thrice weekly. Valuation of production The valuation of production will require the measurement of biomass produced. The procedure for su ch measurement will begin at the 136

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po int of harvest for the plants produc ed. The plants will be harvested by hand. They will then be prepared as fo r market as noted in their species profile. The plants will be rinsed in fresh water, and then dried in a retrofitted rotary salad drier. They will be then weighed to obtain their equivalent final market va lue weight. This weight wi ll be used to value the production of the system to the value of the same product if purchased in the marketplace. This value can then be compared against the cost of building and operating the system to yield a time value to the system output. The market value of the greens pr oduced will be compared against the average prices offered for the same products sold by large produce distributors located on opposite coas ts of the United States in Febuary 2008. The final value of produce will al so take into account the cost of seed used. Table 9: Assessed market value for vegetative produce 137

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A rugula Eruca sativa o z 0.1 5 $ A rugula, microgreen Eruca sativa o z 0.84 $ Basil, MicrogreenOcimum basilicumo z 2.99 $ Basil, SweetOcimum basilicumo z 3.99 $ Chives A llium schoenoprasumo z 1.99 $ Collards, Georgia SouthernBrassica oleraceaea1.99 $ Dill, Mammoth A nethum graveolenso z 2.6 5 $ India Mustard, Florida Broad LeafBrassica juncea subsp. o z 0.79 $ India Mustard, Florida Broad Leaf, microgreensBrassica juncea subsp. o z 2.99 $ India Mustard, Southern Giant CurledBrassica juncea subsp. o z 0.79 $ India Mustard, Southern Giant Curled, microgreensBrassica juncea subsp. o z 2.99 $ Kale, Dwarf Blue CurledBrassica oleraceaea2.99 $ Kale, Dwarf Blue Curled, microgreensBrassica oleraceao z 2.99 $ Lettuce, Black Seeded SimpsonLactuca sativa subsp. ea2.79 $ Lettuce, Black Seeded Simpson, microgreensLactuca sativa subsp. o z 2.99 $ Lettuce, Burpee Bibb ButterheadLactuca sativa subsp. ea3.89 $ Lettuce, Burpee Bibb Butterhead, microgreensLactuca sativa subsp. o z 2.99 $ Lettuce, Iceberg A Lactuca sativa subsp. ea 1.99 $ Lettuce, Iceberg A, microgreens Lactuca sativa subsp. o z 2.99 $ Lettuce, Parris Island Cos (Romaine)Lactuca sativa subsp. ea2.99 $ Lettuce, Parris Island Cos (Romaine), microgreensLactuca sativa subsp. o z 2.99 $ Lettuce, Salad BowlLactuca sativa subsp. ea2.49 $ Lettuce, Salad Bowl, microgreensLactuca sativa subsp. o z 2.99 $ Mesclun, microgreens, a blend of:o z 2.99 $ Endive, green curled Kale, red Russian Lettuce, red romaine Lettuce, paris island cos Lettuce, salad bowl Lettuce, lolla russa Mint, SpearmintMentha spicatao z 3.99 $ Radish, Cherry BelleRaphanus sativuso z 2.99 $ Spinach, Teton HybridSpinacia oleraceao z $0.31 Valuation of costs 138

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T he cost of the system itself will be calculated by the summation of the total component costs. Costs of operation will be calculated by electrical, water, and feed input costs. 139

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Results System costs T he total component cost for the construction of the system was $659.21. Input costs The system utilized 45 watts of power, 24 hours per day, 240 watts of power for 12 hours per day, and an average of ten gallons of water per week. The national average electric al price is currently $0.0986 per Kilowatt Hour. From the equation: (Watts x 10^-3) x Hours used per day x Cost per Kilowatt Hour X 7 = C We get C, or weekly electrical cost Therefore, the pump running for 24 hours a day at 45 watts: (45 x 10^-3) x 24 x .0986 X 7 = 0.75 The weekly operation of the pump will cost $0.75 The lighting, which uses 240 watts of power for 12 hours per day will equate to: (240 x 10^-3) x 12 x 0.0986 X 7 = 1.99 140

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T he weekly cost for electricity for lighting will be $1.99 Total weekly electricity costs for the system are $2.74 After the initial establishment of the system, weekly water additions amounted to approximately 10 gallons. In America, the average price of tap water is $2 for 1000 gallons (Envir onmental Protection Agency, 2004). Therefore, the price per gallon is approximately $0.002, and for the system design, the 10 gallon week ly water usage comes at a cost of $0.02. Weekly, the system utilized 3 ounces of pelletized fish feed. This feed was readily available and was afforded to the system at cost on a per ounce basis of seven cents per ounce. Weekly feed costs were $0.07. The total weekly input costs for operating the system built were $2.83. 141

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Results from trials T he first trial of the system began one week after the introduction of fish into the system to provide time fo r nutrient effluent buildup. The plants were grown in two separate zones, t he nutrient film technique NFT zone and the microgreen grow zone, of the system and their progress is noted by such. The quantity of seed utilized in the planting and the plantings respective costs are also noted. NFT grow zone First Planting 2/27/08 SpecieQuantitiyCost Spinach, Teton Hybrid2 g 0.97 $ Lettuce, Burpee Bibb Butterhead1.67 g 0.97 $ Mint, Spearmint100 mg0.97 $ Basil, Sweet500 mg0.97 $ 142

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Figure 53 Seeded NFT grow beds, first planting Microgreen grow zone First planting, 2/27/08 First Planting 2/27/08 SpecieQuantitiyCost India Mustard, Florida Broad Leaf4 g 1.94 $ India Mustard, Southern Giant Curled4 g 1.94 $ Radish, Cherry Belle18.75 g 4.85 $ Mesclun7.5 g 4.85 $ 143

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Figure 54 Seeded Microgreen Grow area, first planting 144

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First harvest 3/5/08 NFT grow zone Not yet of harvestable size Figure 55 Sprouting Basil, NFT grow zone, first planting Figure 56 Sprouting Spinach, NFT grow zone, first planting 145

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Figure 57 Sprouting Bibb lettuce, NFT grow zone, first planting Figure 58 Sprouting Mint, NFT grow zone, first planting Microgreen grow zone FIRST HARVEST 3/5/08 SpeciePlantedHarvest India Mustard, Florida Broad Leaf4 g 7 4 India Mustard, Southern Giant Curled 4 g 6 9 Radish, Cherry Belle 18.75 g 27 7 Mesclun 7.5 g 15 4 146

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Figure 59 Radish and Mustard Micro green bed prior to first harvest 147

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Figure 60 Mesclun and Mustard microgreen grow beds prior to first harvest Figure 61 Sprouted Basil and Bibb lettuce NFT grow troughs 148

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Figure 62 Bibb lettuce grow trough, showing many sprouts prior to thinning Figure 63 Sprouted NFT grow troughs 149

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Second harvest from first planting amount and value 3/12/08 NFT grow zone Not yet of harvestable size Microgreen grow zone Secondary growth cycle resulting fr om previously un-germinated, but sown, seeds. SECOND HARVEST 3/12/08 Specie Plante d Harvest (g) India Mustard, Florida Broad Leaf 4g 72.40 India Mustard, Southern Giant Curled 4g 75.50 Radish, Cherry Belle 18.75g 302.10 Mesclun 7.5g 173.10 150

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Figure 64 Microgreen grow beds prior to second harvest from first planting TOTAL HARVEST SpeciePlantedHarvest (g)CostValu e Net Value India Mustard, Florida Broad Lea f 4 g 147.301.94 $ 15.54 $ 13.6 0 $ India Mustard, Southern Giant Curled4 g 145.001.94 $ 15.29 $ 13.3 5 $ Radish, Cherry Belle18.75 g 579.204.8 5 $ 61.09 $ 56.2 4 $ Mesclun154.8 g 327.904.8 5 $ 34.58 $ 29.7 3 $ 151

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Figure 65 Radish microgreen grow bed ready for second harvest from first planting 152

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Figure 66 Mesclun grow bed ready for second harvest from first planting System Destruction On April 5th the system was destroyed by high winds. The conditions resulted in the NFT channels being blown off of the A-frame, and the net pots and young plants scattered about the research area. The destruction was not discovered until the pl ants had become desiccated and perished. The fish were not affected. The system was rebuilt but the crops had to be replanted. Assuming the plants were grown to maturity, approximately an additional three we eks, production values would have been as follows. 153

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TOTAL HARVEST SpeciePlantedHarvestCostValueNet Value Basil, Sweet500 mg120 oz.0.97$ 478.80$ 477.83$ Lettuce, Burpee Bibb Butterhead1.67g60 ea.0.97 $ 233.40$ 232.43$ Mint, Spearmint100 mg120 oz.0.97$ 478.80$ 477.83$ Spinach, Teton Hybrid2 g 120 oz.0.97 $ 37.20 $ 36.23 $ The assumptions made in these calculations are: all plants would grow to harvestable size, in addition that instead of a continued harvest as is possible with the mint and basil, that only two harvests of each plant, amounting to one ounce each woul d be taken. In addition, the theoretical harvest of the spinac h would occur when the plants had amassed two ounces worth of leafy gr owth, although the theoretical yield of each plant is substantially higher. System rebuild After the destruction of the system, a partial rebuild took until 4/11. During the rebuilding of the system t he filter material substrate, in the microgreen grow section, was replaced with common sand found locally. The sand was washed in a bleach so lution, then fresh water before being used to fill the grow sections to the same level that the mats had occupied. This change was made to el iminate rotting root matter found in the filter material substrate, as we ll as to more evenly maintain water levels, ensuring a more even sprouting environmen t and preventing secondary germination periods. 154

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Replanting The system was replanted on 4/14. NFT Planting SpecieQuantitiyCost Arugula1.67 g 0.97 $ Basil, Sweet500mg0.97 $ Chives500mg0.97 $ Collards, Georgia Southern1.67 g 0.97 $ Dill, Mammoth1.67 g 0.97 $ India Mustard, Florida Broad Leaf2 g 0.97 $ Kale, Dwarf Blue Curled1.67 g 0.97 $ Lettuce, Black Seeded Simpson1.67 g 0.97 $ Lettuce, Burpee Bibb Butterhead1.67 g 0.97 $ Lettuce, Parris Island Cos (Romaine)1.67 g 0.97 $ Lettuce, Salad Bowl1.67 g 0.97 $ Mint, Spearmint100mg0.97 $ Radish, Cherry Belle2 g 0.97 $ Spinach, Teton Hybrid2 g 0.97 $ Microgreen Planting Specie Quantitiy Cost Radish, Cherry Belle 21g $ 1.41 First Harvest 4/21 NFT Grow Zone Not yet ready for harvest 155

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Figure 67 NFT grow bed, sprouted, second planting Microgreen Grow Zone Total Harvest SpeciePlantedHarvest (g)CostValueNet Value Radish, Cherry Belle21g2,125.201.41 $ 224.14$ 222.73$ 156

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Figure 68 individual microgreen grow bed, planted with radish, ready for harvest Figure 69 Volume comparison of harvested radish microgreens from a single grow bed against a six-inch ruler 157

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System Status 5/7/08 NFT Grow Zone Steady, strong growth was exhibited in all plants, however, no plant was of harvestable size. The valuation of possible production is as follows: Hypothetical NFT Harvest SpeciePlanted Qty Pots Planted HarvestCostValueNet Value Arugula1.67g1224 oz0.97 $ 3.60 $ 2.63 $ Basil, Sweet500mg2448 oz0.97 $ 191.52 $ 190.55 $ Chive s 500mg1224 oz0.97 $ 47.76 $ 46.79 $ Collards, Georgia Southern1.67g1212 ea0.97 $ 23.88 $ 22.91 $ Dill, Mammoth1.67g1224 oz0.97 $ 63.60 $ 62.63 $ India Mustard, Florida Broad Leaf2g1224 oz0.97 $ 18.96 $ 17.99 $ Kale, Dwarf Blue Curled1.67g2424 ea0.97 $ 71.76 $ 70.79 $ Lettuce, Black Seeded Simpson1.67g2424 ea0.97 $ 66.96 $ 65.99 $ Lettuce, Burpee Bibb Butterhead1.67g2424 ea0.97 $ 93.36 $ 92.39 $ Lettuce, Parris Island Cos (Romaine)1.67g2424 ea0.97 $ 71.76 $ 70.79 $ Lettuce, Salad Bowl1.67g2424 ea0.97 $ 59.76 $ 58.79 $ Mint, Spearmint100mg1224 oz0.97 $ 95.76 $ 94.79 $ Radish, Cherry Belle2g1212 oz0.97 $ 35.88 $ 34.91 $ Spinach, Teton Hybrid2g1224 oz0.97 $ 3.72 $ 2.75 $ 848.28 $ 834.70 $ The assumptions made in these calculations are as made before: all plants would grow to harvestable size, in addition, that instead of a continued harvest as is possible with the arugula, basil, chives, dill, mustard, mint, and spinach that only two harvests of each plant, amounting to one ounce each woul d be taken. In addition, the theoretical harvest of the Radishes would occur when the plants had amassed a combined weight of twelve ounces. Microgreen Grow Zone 158

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Use had been d iscontinued afte r the previous harvest in preparation for experiment cessation. 159

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Discussion Verify or falsify hypothesis T he systems was successfully constructed and operated in a manner which could have defrayed it s construction and operating costs and would be suitable for operation in or around a domicile. Total value for operation The total value for all produced greens, less seed cost, was $2394.67. Running for ten weeks at a weekly operating cost of $2.83, resulted in a total operating expense of $28.30, added to the cost of construction of the system, $659.48, a total system expense of $687.78 was incurred. However, when valued agains t the profit/savings derived from the system output, a net ga in of $1706.89 was realized. Second harvest from first planting Due to the uneven nature of the filt er material used as grow media in the initial planting of the mi crogreen grow system, not all seeds received adequate moisture evenly. This resulted in a second cycle of germination and growth, reducing overa ll system productivity by forcing a decision between investing more time to grow the same sown seeds or the disposal of an unknown quantity of seeds, both of which negatively 160

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f iscally impact the system Because of this media inadequacy for multiple uses, the system design was re-evaluated to test sand as a reusable microgreen grow media. Sand as microgreen grow media Before testing in the system, literatu re research into the use of sand as microgreen grow media had revealed previous experimentation. While noted for its functionality as a grow substrate, previous research had indicated difficulties when attemp ts were made to harvest the microgreens. The harvesting process was found to be unreliable in the exclusion of the sand media from the mass of final produce (Morgan, 2008). Despite the results of previous research sand media was selected as a grow media for the microgreen grow section of the system. As reported by earlier research, it proved to be extremely effective for microgreens production. Most notable was the ease with which the media level and water level could be coordinated to ensure uniform sprouting of seeds. At the time of harvest a unique approa ch was devised to ensure removal of all media from final produce. Rather th an the traditional harvesting of the plants from the media, the contents of the grow tray were placed in a large bucket. This bucket was then flood ed with cool water and agitated. The result was the separation of plan t material and grow media, with the microgreens floating to the surface of the water and the grow media 161

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settl ing to the bottom. The microgreens were then removed and washed again in a clean container of water before being dried and prepared as stated in the methods section. The resulting produce was found to have no detectable media remaining after processing. The ready availability, low cost ease of sterilization, and effectiveness of sand as a grow medi a make it an idea l choice for many inorganic media cropping methods. In terms of availability there is no grow media as readily available to the cropper as sand. With further research it may be possible to integr ate the use of sand as a replacement for other types of grow media in most hydroponic and aquaponic cropping systems. This could potentially provide numerous new opportunities for both commercial an d domestic producers, reducing their operating and initiation costs, allowing for greater potential benefit and return from such systems. Spacing concerns with varied crops Many of the species which were grown in the system have accurately determined spacing requir ements for proper growth in normal soil culture. These requir ements, however, were calculated on the basis of normal horticultural practices. Incorp orated into these calculations are the estimated availabilities of nutrients found in soil. While soil may be forced, by culturists, to have, at least at times, high nutrient content, unlike 162

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in an aquaponi c nutrient solution, it is relatively static, therefore, spacing limitation due to nutrient availability is much different in an aquaponic system; nevertheless, growing space fo r each plant must be determined, complete studies of which have yet to be undertaken for aquaponic cropping. In an aquaponic system t he only space needed by the plant is that which will be filled by actual physical growth. The system tested was designed to provide each plant with sixteen square inches of growing space. While adequate for the species te sted it may not be suitable for all species desired by a different experimenter and spacing therefore may need to be adjusted based on desired grow species. Another factor in plant selection and crop rotation is variations in vertical growth height and shape. Species which grow quite tall or broad are unsuitable for planting closely amongst other, shorter, species for they would shade and hinder the latters growth. Accuracy of results with indirect light The location of the experimental sy stem resulted in the plants being exposed to horizontal indirect sunlight on a daily basis, and occasional fluorescent lighting. While this may ha ve led to possibly improved growing conditions, the same effect could be observed should the system have been constructed in an occasionally -lit room with windows, as is commonly found in domestic settings. Wh ile it was not feasible to control 163

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nor calculate the i nput from external lighting, in the form of dispersed fluorescent light and indirect sunlight, the error caused by this Is believed to be minimal due to examined total lack of external plant growth in the research area. Temperature fluctuation The system design and purpos e was constrained by factors intended to limit its scale to a size feasible for an indoor setting in a household. However such confined space was not available at the research facility and the study had to be conducted outdoors. There, the system was subjected to much grea ter climatic variation than in a controlled interior setting. However, this variability is believed to have resulted in reduced system productivi ty due primarily to low temperatures, and resulted, from wind damage, in the total destruction of one test run of the system, and is not a contributing fa ctor in the positive performance of the system. Value as a hobby or pastime The value of the system as a form of recreation is not possible to calculate as an approximated number In every conceivable instance it would be highly variable. For some persons operating such a system maintenance would be considered a chore and merely a means to save money or provide otherwise unavailabl e produce, for others the system 164

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could offer an enj oyable pastime. Assuming an enjoyment of system operation on the behalf of the user, the productivity of the system would be increased by its additional re creational value to the user. Actual value of goods produced, Trend/geographically distorted value on produce System product valuation is not ea sily calculated. There are many factors affecting the value of the prod uction of the system. A person who would rarely purchase vegetables, for instance, would receive less benefit from the system than a vegetarian individual with a preference for organic produce. Actual value of goods produced may not reflect the actual purchasing tendencies of the individual utilizing the system and therefore the species and system scale may not be applicable in every circumstance. An individual interested in production of only a single species may require a smaller system to meet their demand. Specialty cropping methods, such as microgr een production may only be of high value to the culinary enthused indivi dual. Although the plants produced may be of green cropping stan dards and accordingly valued, the individual operating such a system may not desire such produce, and therefore, proper production pricin g levels would be decreased. Produce values are also geographically and to an extent seasonally distorted. In areas of high agricultural production average prices would 165

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be deflated whi le in less agricultural regions prices would be inflated. In addition, prices would be variable by regional production seasons, inflating and deflating as production varied. Costs reduction / modification Many of the components used in this system are recycled from laboratories, however, in order to calc ulate the productivity of the system, their costs, new, are included in the ex perimental trial. In addition, these higher values and incorporated costs more effectively test the possible viability of the system. In a ho usehold environment, less expensive alternatives, or recycled components may be selected. For example, the fiberglass tanks for fish containment which cost $130, could have been replaced with Rubbermaid storage bins or plastic trash cans for under $30. In addition, the polyester filter material could have been replaced with washed beach sand or gravel, as tested in the experimental, even discarded cloth could function as capillary matting and short term grow medium. In addition, fish for the system, could, allowing for local regulation, be procured for possibly no cost from loca l water bodies, as was done for this experiment. Evaluation of disconnect from household While the system was designed for use in the home, it was constructed and operated at a labora tory, outdoors. It was, however, 166

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sh ielded from most weather, and was in an area with little ambient light. It is unlikely that the system benefitted from these conditions and, in fact, would likely produce more effectively in the controlled environment of the home. Notes relating to previous research Research conducted by the Univ ersity of the Virgin Islands concludes similar findings to those of th is experiment in th at it relatively small populations of fish, when well fed, is capable of supporting an extremely large area of plant growth. Previous research, conducted by Pe ter Thiesen, had suggested that indoor lighting for small scale aquapo nics would be productive if more expensive, high-intensity discharge, metal halide, lighting systems were utilized. Through this body of research we are able to conclude that dependent on species and system design it is possible to use less expensive fluorescent lighting fixtures to successfully produce vegetables. Design notes The vertically aligned A-frame style NFT trough system proved to be extremely effective, howe ver it was found that in areas with climactic weather conditions the system must be strapped together extremely rigidly, else the system runs the risk of quite literally being blown to pieces 167

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i n a gale. It was however, and extrem ely versatile grow design, safely and productively harboring many culture sy stems in a small volume of space. The design of the experimental syst em originally featured relatively small independent grow beds for microgreen production, this system design feature, originally intended to allow for more accurate production measurements was found to provide potential benefits to an ordinary grower, not just the experimenter. By having the grow beds separated and individually removable, the abil ity to incorporate staggered grow regiments was greatly facilitated. A system featuring as few as six or seven such grow beds would enable a regiment of daily single bed harvesting, without the need to dist urb other grow beds, providing for uninterrupted daily microgreen producti on. In addition, by having such a grow bed arrangement, system bio-secu rity is increased by allowing the cropper to isolate and eliminate indi vidually affected portions of the vegetative production process wi thout total system cleansing. Additionally, isolated grow beds promote easy gross species separation, eliminating the possibility of cross population of culture organisms. Suggestions for future work The results from this experiment open the pathway to numerous future projects. The productivity of this system was beyond expectations and would encourage much greater im plementation and modification of 168

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the system. T he design of the test sy stem was based on examined density requirements for complete growth of certain plant species and calculated exploitable space in a domicile. If these constraints are removed, according to experimental re sults, system productivity could be increased for certain types of production, most notably the intensive production of microgreens. Microgreen grow systems would be one of my next projects. The microgreen section of the tested sy stem produced at the highest value and greatest speed, not only making it more productive, but more enjoyable to operate. For my next system I would like to construct a mobile growth system in which the microgreen grow trays are slowly moved past a light and nutrient source, or alternatively, a mobile lighting system. The ultimate goal of the next project would be to attempt to maximize productivity of micr ogreens in a given space. Small-scale microgreen production sy stems are of potential benefit in the restaurant marketplace, a llowing for a potential in-house production of both herbs and other plants for use on site. While other means of acquisition of such produce may be available to such commercial consumers, benefits may still be obtained through the construction and operation of such a system. Such a system would enable the user to ensure a constant supply of top quality produce with 169

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total qual ity control. In addition, the system would allow for compensation to rapid changes to fluctuating consumer demand. Such systems, as tested in this experiment, utilize exceedingly small amounts of water when compared to tr aditional farming techniques. This notable feature of these technologies could be of great potential benefit to individuals residing in aerated locati ons. In such regions, where water is at a premium, more efficient grow methods would be extremely valuable to the inhabitants. Through the im plementation of such agricultural advancements, water use could be reduced, vegetative output to be increased, or potentially both. Fu rther study would be required into system design and plant physiology to be better able to accurately judge water consumption by such systems. In addition, depending on system design, it may be possible to re capture water lost through plant transpiration. This could possibly be facilitated through greenhouse construction or simple plastic tenting systems functioning as solar stills to recapture moisture from the air. With further research the potentia l productivity of natural plant transpiration may be better quantified. The transpiration of plants, particularly in systems such as t hese which are easily contained, may provide additional benefit to the user. In areas with little or no potable water, it may be possible to utilize an aquaponics system as a means of 170

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natural b iofiltration to produce wa ter suitable for human or animal consumption. Further study is needed to better understand the effects of contaminated water on the products of such a system, including studying to the safety of the grown pr oduce and potential remaining contamination of transpired water. Furthermore, research should be conducted into the effective use of other species liquid wastes, such as animal and human, as nutrient solution for inorganic medium grow systems. If found viable, the sizes of such systems as the one tested in this experiment could be greatly reduced through the elimination of the fish containment system, instead utilizing a simple effluent reservoir to provide nutrient supply to the grow beds. Although conceivably interpretable as both morally and socially uncouth, such a system utilizing readil y available effluent nutrient solution could be effectively implemented as a means of food and water production in areas where either fi sh are unobtainable, or resource distribution infrastructure has been dest royed, such as in disaster stricken regions. Additionally, I would like to investigate the possibility of utilizing solar powered pumps to operate the system. Such a system, utilizing solar power, would enable standalone prod uction capabilities. A system requiring no input of electrical energy on the behalf of the user would 171

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ob viously result in an increased in va lue of the net product of the system. Such a system however would not be able to be situated indoors unless the solar collection array was located in an area which received sunlight. While obviously a system which woul d conceivably benefit any domestic or commercial aquaponic producer, ther e are additional benefits to such an "off the grid" design. Such a system would enable a user located in areas where electricity is unavailable to produce food on a higher productive level typically reserved for more intensive and developed production techniques and location s. Much of the underdeveloped world suffers from a lack of readily available food, let alone proper nutrition, and such a system would enable in-house vegetable production, even in areas of relatively high population density, without the need of such modern luxuries as electricity or running water. Through further research it may be possible to prove that a system such as the one tested, integrated with solar power systems could continue to meet a households vegetable needs at a lower cost, or even on a fiscally productive level in impoverished areas around the globe. If proven effective the system could conceivably become a crutch in the global fight against starvation and malnutri tion, aiding in increasing global standards of living. Though government sponsored programs and humanitarian non-governmental orga nizations, distri bution of fully constructed systems, bulk seed, and technical knowledge of the field 172

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could be prov ided, in lieu of or in ad dition too current food aid, with the goal of, over time, promoting self sustainability through integrated agricultural production practices. If such a stand-alone system is tested and found productive, particularly in terms of microgreen production, a potential exists for the system to play a vital role in disa ster relief and recovery operations. Systems such as the one tested could be easily prefabricated and packed for insertion in disaster stricken regions. For microgreens production the system tested was found to be capable of producing, within five days, large amounts of consumable produce from extremely modest sources. In one trial run 21 g of seed was planted in an 11x16 grow bed; this single planting produced 2125.2 g of consumable vegetative growth in an extremely shor t period of time, a productive mass increase of 10020%. Such systems inserted into disaster stricken regions would enable, very rapidly, on-site prod uction of large quantities of fresh produce from relatively small comp onents. As well as establishing immediately the basic infrastructu re for longer-term recovery and rebuilding through the production of food, the ground-floor injection of modern integrated agriculture technolo gy could benefit the rebuilding of the regions agricultural industry encouraging it to become more productive, both benefiting the local population through increased food production, and possibly making t he area competitiv e in the global 173

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agr icultural marketplace, possibly leading to a higher standard of living for the population of the affected peoples. 174

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Conclusions Domest ic scale aquaponics is a reality and can be successful for the home. The systems would need to be made more presentable, and the noise of the falling water may need to be dampened or eliminated through the use of mechanical aeration, but the systems are viable none the less. Domestic scale integrated agriculture systems could be of great benefit to persons living in nort hern climates, providing them fresh vegetables without the need for the lo cal grocery. The benefits presented to lower income households would be significant. Along with providing lower cost vegetables to such househo lds, the system would be able to provide a higher priced class of vegetable at a lower cost than the purchase price of minimum reco mmended levels of vegetable consumption. Possibly of greater valu e from the system are the potential befits afforded the user in less-develo ped countries, where, the potentially reduced produce costs and possible in crease in productive output may assist individuals in not only prov iding their barest of nutritional requirements, but possibly allowing fo r a higher day to day standard of living they could not otherwise afford. 175

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Appendix A: Mater ials used study: physical system components Ite m Cost eachQTYTotal cost 4 pvc wastewater pipes10.73 $ 10107.30 $ 4 pvc water pipes15.57 $ 115.57 $ 2 pvc water pipe5.4 5 $ 1 5.4 5 $ 2x4 lumber, not pressure treated2.3 9 $ 716.73 $ sawhorse kit4.4 9 $ 1 4.4 9 $ insulation sheets10.49 $ 220.98 $ 65 gallon rectangular fiberglass tanks65.00 $ 2130.00 $ All weather deck paint, 1 quart10.00 $ 110.00 $ All weather deck screws, 1 box, ace hardware4.4 9 $ 1 4.4 9 $ pvc 4 endcaps1.0 9 $ 4 4.36 $ pvc bushin g 1.17 $ 11.17 $ pvc male adaptor0.43 $ 10.43 $ pvc fittin g 1.27 $ 11.27 $ pvc plugs1.83 $ 23.66 $ Water pump69.00 $ 169.00 $ fluorescent light fixtures8.7 9 $ 326.37 $ grow lights9.9 9 $ 439.96 $ grow lights9.8 8 $ 219.76 $ light timer6.9 5 $ 1 6.9 5 $ power strip2.46 $ 12.46 $ 3 way electrical outlet splitter0.97 $ 10.97 $ Filter bag, felt, 1 micron6.0 5 $ 1 6.0 5 $ 1 vinyl tubing, 51.32 $ 5 6.60 $ 25pk plated brass valves29.29 $ 129.29 $ 3/16 silicone aquarium tubing, per foot0.36 $ 3010.80 $ Plastic storage tubs4.00 $ 416.00 $ 1x36x6, fine grade polyester filter material15.55 $ 115.55 $ Pvc cement4.9 9 $ 1 4.9 9 $ Silicone sealant3.4 9 $ 1 3.4 9 $ Rockwool propagation cubes11.83 $ 335.49 $ Plastic coated Paperclips0.8 8 $ 1 0.8 8 $ 25pk 2 net pots2.90 $ 1029.00 $ PVC Cement9.97 $ 19.97 $ 659.48 $ Physical System Components 176

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Appendix B: Clar ification and definition of physical system components 4 inch PVC wastewater pipes Thin-walled polyvinyl chloride piping with a diameter of 4 inches, used for waste water return in plumbing systems, intended for use as grow troughs. 4 inch PVC water pipes Heavy walled pressure rated polyvinyl chloride piping with a diameter of 4 inches, for use as wate r return troughs from the 4 inch PVC wastewater pipes. 2 inch PVC water pipe Heavy walled pressure rated polyvinyl chloride piping with a diameter of 2 inches, to be used as the primary water distribution pipe. 2 x 4 lumber 2 x 4 x 10 pine lumber was selected for frame construction. Of note was the selection of non-pressure treated lumber to eliminate the possibility of chemical leaching into the water of the system. 177

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Sawhorse kit A simple, preformed, metal jointing ki t intended to allow 2 x 4 legs to attach to a 2 x 4 cross member. Insulation sheets Plastic film coated, ri gid foam insulation s heeting, 4 x 8, was selected as an anchor material for the net pots in the grow troughs. 65 gallon rectangular fiberglass tanks These tanks were selected for their availability and structural integrity under UV light. All weather deck paint Heavy acrylic deck paint was selected as the optimal sealant for the system to ensure the integrity of the wooden frame against possible water damage. All weather deck screws Deck screws were selected for system construction due to their construction and coating, which pr events them from oxidizing and possibly leaching contam inants into the system. PVC 4 inch end caps 178

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Polyvinyl chloride caps to seal the ends of the 4 PVC Water pipes. PVC bushing A 2 to 1 female threaded polyvinyl chloride bushing for the water distribution system. PVC male adapter A 1 inch male threaded polyvinyl chloride fitting intended for the water distribution supply pipe. PVC fitting A 2 inch, three way, polyvinyl chloride pipe connector for the water distribution system. PVC 2 inch plugs Two, 2 inch polyvinyl chloride pipe plugs to seal the water distribution system and maintain system pressure. Water pump The water pump selected for th e system was a Supreme brand, model MD5 pump, rated to operate at 500 gallons per hour on 45 W of electricity. The pump features a magnetic impeller which reduces maintenance and is extremely energy efficient. 179

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Fluorescent light fixtures Inexpensive, 48 inch, workshop style fluorescent light fixtures selected both for their cost, and thei r hanging design. The design of the lights allowed them to be easily posi tioned at a more efficient angle of the grow troughs Grow lights Six general spectrum grow lights, 48 inches in length, were purchased. The bulbs were purchase d from two sources due to limited supply, resulting in different costs for the bulbs. Light timer A household electrical timer was purchased to automate the daily lighting cycle over the grow system. Power strip A common household surge protector to ensure electrical security of the system. Three way electrical outlet splitter Common household grounded electrical splitter, to be used to attach the three lighting fixtures to the electrical timer. Filter bag, felt, 1 180

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A commonly av ailable aquarium filt er bag, made of polypropylene felt, 32" x 7", capable of filtering so lid waste as fine as 1 was purchased to house the water distribution pump and provide mechanical filtration for the system. 1 inch vinyl tubing 5 feet of 1 inch, UV stabilized vi nyl tubing was purchased to supply water to the water distribution pipe from the pump. 25 pack plated brass valves 25 nickel plated brass valves were purchased for the main water distribution pipe, featuring an adjust able knob to control water flow and allow easy cleaning of the valve itself The valves were male threaded to male tube fitting for 3/16" tubing. 3/16" silicone aquarium tubing 30 feet of 3/16" silicone aquarium airline tubing was purchased for the purpose of water distribution and return. Plastic storage tubs Inexpensive 11 x 16 inch plastic tubs were purchased as grow containers for microgreens Fine grade polyester filter material 181

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A 1" x 36" x 6' secti on of fine grade polyester filter material was purchased to act as capillary mattin g and grow medium for microgreens. Silicone sealant Silicone sealant was purchased and used to maintain structural integrity and positioning of system components. Rockwool cubes Rockwool, or what is occasionally referred to as Stonewool, propagation cubes are cubes of spun molten rock which is then allowed to cool. Crushed rock is heated to temperatures exceeding 1600C then extruded through high-speed spinning wheels forming masses of intertwined fibers, a process often compared in likeness to the production of cotton candy. Rockwool is an ideal rooting me dium for plant growth due to its capability of holding, simultaneously great quantities of air and water, allowing for ample nutrient and gas uptake by the plants roots. In addition, due to their spun construction and interwoven fibers, they provide a relatively secure mechanical fixation to maintain plant stability. 2 Rockwool cubes were purchased to act as grow medium in the NFT troughs of the systems. Net pots 182

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Net pots are s imple pots made of molded plastic mesh and are commonly used in hydroponic syst ems to contain rockwool cubes. Chemically inert, they act as the anchors fixing Rockwool cubes to hydroponic systems. 183

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Bibliography ACNielsen Homescan data How Much Do Americans Par for Fruits and Vegetables [Report]. [s.l.] : Econ omic Research Service, USDA, 2000. Adler Paul R Overview of Economic Evaluati on of Phosphorus Removal by Plants [Journal] // Aquaponics Jo urnal. Mariposa : Nelson/Pade Multimedia, 2001. 4 : Vol. V. pp. 15-18. Adler Paul R. Phytoremediation of Aquaculture Effluents [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 1998. 4 : Vol. IV. pp. 10-15. Barker Allen V and Pilbean David J Handbook of Plant Nutrition [Book]. New York : CRC Press, 2007. Beck Charles B An Introduction to Plant Stucture and Development [Book]. New York : Cambridg e University Press, 2005. Bell Frederick W Food From the Sea: The Ec onomics and Politics of Ocean Fisheries [Book]. Boulde r : Westview Press, 1978. Bidwell R.G.S. Plant Physiology [Book]. Ne w York : Macmillon Publishing Co., Inc., 1974. 184

PAGE 195

Blisard Noel, Stewart Hayden and Jolliffe Dean Low -Income Households' Expenditures on Fruits and Vegetabl es [Report]. [s.l.] : Economic Research Service, USDA, 2007. Brister Deborah J and Kapuseinski Anne R Organic Aquaculture [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2000. 5 : Vol. IV. pp. 18-21. Brister Deborah J Organic Aquaculture Upda te; The National Organic Standards Board Aquatic Animal Task Force: Reccomendations on Operations that Produce Aquatic Animals [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 2001. 4 : Vol. V. pp. 2630. Burns Robert Raising to Tilapia in Small Gr eenhouse's Promises Profits for Texans [Journal] // Aquaponics Journal. 1997. pp. 3-5. Cancio-Bello Tara Growing Perennial Herbs Hydroponically [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 1999. 4 : Vol. V. pp. 20-21. Colgate Myra D Aquaponics Course Inspires Attendees [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2001. 1 : Vol. V. pp. 14-19. 185

PAGE 196

Creaser Gordon Aquapon ics Suriname [Journal ] // Aquaponics Journal. 2000. pp. 22-24. Creaser Gordon Aquaponics Suriname... the Adventure Continues [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2001. 1 : Vol. V. pp. 20-22. Creaser Gordon Commercially Viable Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 1998. 4 : Vol. IV. pp. 7-9. Creaser Gordon Developing Aquaponics Syst ems [Journal] // Aquaponics Journal. 2000. pp. 20-21. Creaser Gordon Float Systems [Journal] // Aquaponics Journal. 1997. pp. 18-20. Creaser Gordon Home Hydroponic Unit [Journ al] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 1999. 3 : Vol. V. pp. 16-19. Creaser Gordon Hydroponics in Honduras Upda te [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 2000. 1 : Vol. IV. pp. 1213. Creaser Gordon So, you Want to Grow Lettu ce? [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1999. 5 : Vol. V. pp. 2224. 186

PAGE 197

Creaser Gorndon Hydropon ics in Hondouras [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1999. 4 : Vol. V. pp. 1516. Creaser Gorndon So, You Want to Grow Herbs? [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 2001. 2 : Vol. V. pp. 1416. Daniels Warner Food from Small Places [Journ al] // Aquaponics Journal. 1997. pp. 4-7. Eastwood Tom Soilless Growth of Plants, 2nd edition [Book]. New York : Reinhold Publishing, 1947. Environmental Protection Agency Drinking Water Costs & Federal Funding [Report]. [s.l.] : United States Environmental Protection Agency, 2004. Evans David H Physiology of Fishes [Book]. Ann Arbor : CRC Press, 1993. Fichter George S Underwater Farming [Book]. Sarasota : Pineapple Press, Inc, 1988. Fitzsimmons Kevin Global Update 2008: Tilapia Production, Innovations, and Markets [Report]. Orland o : Aquaculture America, 2008. Food and Agriculture Organization of the United Nations Report of the FAO Technical Conference on Aquacultur e [Conference] // FAO Fisheries 187

PAGE 198

Report No 188. Kyoto : Food and Agri culture Organization of the United Nations, 1976. pp. 2-43. Franks Douglas Fish, Facts and Fun, at the UVI Short Course [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2001. 4 : Vol. V. pp. 23-25. Galston Arthur W Life Processes of Plants [Book]. New York : Scientific American Library, 1994. Gilroy Simon and Masson Patrick H Plant Tropisms [Book]. Oxford : Blackwell Publishing, 2008. Goes Stefan Build a Hobby System [Journ al] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2002. 4 : Vol. vi. pp. 14-19. Goowin T.W. and Mercer E.I. Introduction to Plant Biochemistry [Book]. New York : Pergamon Press, 1972. Hanson Gene P The Fish "Condition Factor A Business Managment Tool [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 1999. 3 : Vol. V. pp. 12-15. Harmon Todd A Look at Filtration in Aq uaponic Systems: Bead Filters [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2001. 23 : Vol. V. pp. 16-19. 188

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Harmon Todd NFT Aquaponic Systems: A Closer Look; The Land, EPCOT, Walt Disney World, Orlando, Florid a [Journal] // Aquapo nics Journal. Mariposa : Nelson/Pade Multimedia, 2003. 4 : Vol. VII. pp. 8-11. Harston Myles Developing an Aquaponic Syst em [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1999. 4 : Vol. V. pp. 1719. Harston Myles PVC... A Versitile Option for Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2001. 4 : Vol. V. pp. 19-22. Hoepler Adam Re-Vision Urban Farm [Journal ] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2003. 3 : Vol. VII. pp. 6-12. Hutchings Eric Aquaponics Research on the Praries; Brooks, Alberta, Canada [Journal] // Aquaponics Jo urnal. Mariposa : Nelson/Pade Multimedia, 2003. 4 : Vo l. VII. pp. 12-17. Hutchins Eric Aquaponics in Alberta [Journ al] // Aquaponi cs Journal. Mariposa : Nelson/Pade Multimedia, 2001. 2 : Vol. V. pp. 42-43. Inland Water Fisheries and Aquaculture Service, Fishery Resource Division, FAO Fisheries Department State of World Aquaculture 2006 [Report]. Rome : Food and Agriculture Organiza tion of the United Nations, 2006. 189

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Iwama G.K. [et al.] Fish Stress and Helath in Aquaculture [Book]. New York : Cambridge Univ ersity Press, 1997. Jones Jr J. Benton Hydroponics A Practical Guide for the Soiless Grower Second Edition [Book]. Boca Raton, FL : CRC Press, 2005. Jones Scott and Nelson Rebecca Build a Low Cost, Aquaponic System [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2001. 3 : Vol. V. pp. 10-14. Jones Scott Build Your Own Low-Cost Aq uaponics System [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 1997. 2 : Vol. 1. pp. 6-9. Jones Scott Building Materials for Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 2001. 2 : Vol. V. pp. 1719. Jones Scott Evolution of Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2002. 1 : Vol. vi. pp. 14-17. Jones Scott Filling Your Aquaponic Grow Bed [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1999. 6 : Vol. V. pp. 1823. Jones Scott Getting Tanked [Journal] // Aquaponics Journal. 1997. pp. 15-18. 190

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Jones Scott Mak ing Your Grow Beds [Journ al] // Aquaponi cs Journal. Mariposa : Nelson/Pade Multimedia, 1999. 3 : Vol. V. pp. 20-23. Jones Scott Stepping Stones to Commercial Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2002. 1 : Vol. VI. pp. 22-27. Jones Scott Stepping Stones to Commercial Aquaponics part 1 [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2002. 1 : Vol. VI. pp. 22-24. Jones Scott The Aquaponics Team [Journ al] // Aquaponics Journal. 1997. pp. 11-13. Jones Scott The Aquaponics Team: The Pu mp [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1998. 4 : Vol. IV. pp. 2330. Jones Scott The Birth of an Aquaponic Facility [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multim edia, 2001. 1 : Vol. V. pp. 8-13. Jones Scott The Clarifier [Journal] // aquapo nics Journal. 1997. pp. 1415. Karlson Anders [et al.] The Integrated Biosyste m, Montfort Boys' Town, Suva, Fiji [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2002. 2 : Vol. VI. pp. 14-17. 191

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Kendrick Richard E and Frankland Barry Phytochro me and Plant Growth [Book]. London : Edward Arnold, 1976. Landau Matthew Introduction to Aquaculture [Book]. New York : John Wiley & Sons, Inc., 1992. Landers Melvin Aquaponics Without Electric ity [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 2003. 2 : Vol. VII. pp. 2427. Lauch Mark Ready, Set, Fish! [Journal] // Aq uaponics Journal. Mariposa : Nelson/Pade Multimedia, 2002. 4 : Vol. VI. pp. 6-8. Massie Steve Environmentally Friendly Feeds for Aquaponic Systems [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2003. 2 : Vol. VII. pp. 15-17. Mayer Zachary Ocean Arks: From Waste Wate r Treatment to Integrated Food Production [Journal] // Aqua ponics Journal. Mariposa : Nelson/Pade Multimedia, 2002. 4 : Vol. VI. pp. 10-13. McCaskill Jim Plant Nutrient Elements: Growth, Deficiencies and Toxicities [Journal] // Aquaponics Jo urnal. 1997. pp. 20-22. McLaughlin Bert Cut Flowers and Tilapia: An Aquaponics Study [Journal] // Aquaponics Journal. 2000. pp. 12-15: 36. 192

PAGE 203

Merriken Michael Hobby A quaponics [Journal ] // Aquaponics Journal. 2000. pp. 28-29. Methods Development and Quality Assurance Research Laboratory Methods For Chemical Analysis of Wa ter and Wastes [Book]. Washington, D.C. : U.S. Environmental Protection Agency, 1974. Morgan Lynette Grower's Guide to Tiny Gr eens [Journal] // The Growing Edge. 2008. p. 34. Nardo Domenic Di Perlite, It Rocks! [Journal ] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2000. 3 : Vol. IV. pp. 14-15. Nelson Becca Species Profile... Tilapia [Journ al] // The Aquaponis Journal. 1997. pp. 36-37. Nelson Rebecca Aquaponics in the Classroom [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multim edia, 1997. 1 : Vol. 1. pp. 9-11. Nelson Rebecca Australian Red Claw Crayfish [Journal] // The Aquaponics Journal. 1998. pp. 5-6. Nelson Rebecca Desktop Aquaponics [Journal ] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 1998. 1 : Vol. V. pp. 4-10. Nelson Rebecca Disney's Epcot Showcases Hydroponics and Aquaculture [Journal] // Aquaponics Jo urnal. 1997. pp. 10-14. 193

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Nelson Rebecca Four Primary Hydropon ic Growing Methods [Journal] // aquaponics Journal. 1997. pp. 24-25. Nelson Rebecca Growing Food Fish in Aquaponics [Journal] // Aquaponics Journal. 2000. pp. 23-24, 43 Nelson Rebecca Hydroponics to Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1998. 5 : Vol. IV. pp. 2023. Nelson Rebecca Inslee's Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 1998. 5 : Vol. IV. pp. 6-9. Nelson Rebecca L Aquaponics... A Niche in Agri-Tourism [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2001. 3 : Vol. V. pp. 22-25. Nelson Rebecca L Aquaponics... for Fun and Food [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2003. 2 : Vol. VII. pp. 12-14. Nelson Rebecca L Build a Backyard Float Syst em [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 2003. 4 : Vol. VII. pp. 2430. 194

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Nelson Rebecca L Edi ble Water Gardening [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1999. 4 : Vol. V. pp. 2224. Nelson Rebecca L Kirby Creek Ranh Projec t Update [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2002. 3 : Vol. vi. pp. 6-19. Nelson Rebecca L Pacu... The Hungry Herbivore [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 2003. 3 : Vol. VII. pp. 1819. Nelson Rebecca L. Taking the Plunge into Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2000. 4 : Vol. IV. pp. 10-14. Nelson Rebecca Methods of Aquaculture [Journal] // Aquaponics Journal. 1997. pp. 8-10. Nelson Rebecca NFT Lettuce and Herb Conference [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2001. 1 : Vol. V. pp. 26-27. Nelson Rebecca Plant Lighting Basics [Journ al] // Aquaponics Journal. 1997. pp. 15-17. 195

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Nelson Rebecca Spec ies Profile... Basil [Journal] // The Aquaponics Journal. 1997. pp. 40-41. Nelson Rebecca Species Profile... Bass [Journ al] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 1999. 3 : Vol. V. pp. 42-43. Nelson Rebecca Species Profile... Catfish [Journal] // The Aquaponic Journal. Mariposa : Nelson/Pade Mult imedia, 1998. 5 : Vol. IV. pp. 4243. Nelson Rebecca Species Profile... Chives [Journal] // The Aquaponic Jounral. Mariposa : Nelson/Pade Mult imedia, 1999. 2 : Vol. V. pp. 4647. Nelson Rebecca Species Profile... Lettuce [J ournal] // The Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1998. 1 : Vol. V. pp. 4647. Nelson Rebecca Species Profile... Mint [Journal] // The Aquaponis Journal. Mariposa : Nelson/Pade Mult imedia, 1998. 2 : Vol. IV. pp. 4041. Nelson Rebecca Species Profile... Pak Choi [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1999. 4 : Vol. V. p. 43. 196

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Nelson Rebecca Spec ies Profile... Watercress [Journal] // The Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1998. 4 : Vol. IV. pp. 4647. Nelson Rebecca Species Profile..... Koi [Journ al] // Aquaponics Journal. 1997. pp. 38-39. Nelson Rebecca Species Profile...Trout [Journal] // The Aquaponics Journal. Mariposa : Nelson/Pade Mult imedia, 1998. 3 : Vol. IV. pp. 4243. Nelson Rebecca Species Profilefile... Tilapia [Journal] // aquaponics Journal. 199736-37. Nelson Rebecca The History of Hydroponics [Journal] // The Aquaponics Journal. 1997. pp. 14-19. Nelson Rebecca The University of the Virgin Islands Agricultural Research Station [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 1999. 2 : Vol. V. pp. 4-10. Nuttle David A The Peace Technologies... Al galculture, Aquaculture, and Aquaponics [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2003. 2 : Vo l. VII. pp. 20-23. 197

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Nuttle David Aquapon ics: Technology for Food Security and Food Safety [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2002. 3 : Vol. VI. pp. 20-22. Piper Robert G [et al.] Fish Hatchery Management [Book]. Washington, D.C. : United States Department of t he Interior Fish and Wildlife Service, 1982. Poole Trevor B The UFAW Handbook on the Care and Managment of Laboratory Animals [Book]. New York : Churchill Livingstone Inc., 1986. Post George Revised and Expanded Textbook of Fish Health [Book]. Neptune city : T.F.H. Publications, 1983. Putnam Judy, Allshouse Jane and Kantor Linda Scott U.S. Per Capita Food Supply Trends: More Calories, Refined Carbohydrates, and Fats [Report]. [s.l.] : Economic Resear ch Service, USDA, 2005. Rabanal Herminio R History of Aquaculture [Report]. Manila, Philippines : ASEAN/UNDP/FAO Regional Small-Scale Development Project, 1998. Rakocy J.E. [et al.] Development of an Aquaponics System for the Intensive Production of Tilapia and Hydroponic Vegetables [Journal] // Aquaponics Journal. 1997. pp. 12-13. 198

PAGE 209

Rebecca Nelson Plant Nutr ient Elements: Growth, Deficiencies and Toxicities [Journal] // The Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 1998. 3 : Vol. IV. pp. 20-22. Resh Howard M. Hydroponic Food Producti on [Book]. Mahwah, New Jersey : Newconcept Press, 2004. Sedge Michael H Commercialization of the Oceans [Book]. New York : Franklin Watts, 1987. Sedge Michael H Commercialization of the Oceans [Book]. New York : Franklin Watts, 1987. Shultz Charlie R pH, Alkalinity, Hardness and t he Buffering System as they Relate to Aquaponics [Journal] // Aq uaponics Journal. 1999. pp. 4-8. Stickney Robert R Aquaculture: an Introductory Text [Book]. Cambridge : CABI Publishing, 2005. Taylor Hoyet A Review of the UVI Aquaponics Short Course [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 2003. 4 : Vol. VII. pp. 18-21. Theisen Peter A Passion Once Lit, Won't Quit [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multim edia, 1997. 1 : Vol. 1. pp. 6-8. 199

PAGE 210

Timmons Michael B [et al.] Rec irculating Aquaculture Systems 2nd Edition [Book]. Ithaca, NY : Cayuga Aqua Ventures, 2002. Timmons Michael B and Losordo Thomas M Aquaculture Water Reuse Syatems: Engineering Design and Managment [Book]. New York : Elsevier, 1994. U.S. Census Bureau Average Houshold Size: 2004 [Report]. [s.l.] : U.S. Census Bureau, 2004. Van Gorder Steve Small Scale Aquaculture and Aquaponics: The New and Nostalgic [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2003. 3 : Vo l. vii. pp. 14-17. van Gorder Steve Small-Scale Aquaculture and Aquaponics: The New and the Nostalgic [Journal] // Aqua ponics Journal. Mariposa : Nelson/Pade Multimedia, 2003. 3 : Vol. VII. pp. 14-17. Vassilion Marios The Design and Development of Commercially Viable, Fully Controlled and Monitored Artificial Productive Ecosystems [Journal] // Aquaponics Journal. Mariposa : Nels on/Pade Multimedia, 1999. 6 : Vol. V. pp. 10-14. Warren Will BioBarge [Journal] // Aquapo nics Journal. Mariposa : Nelson/Pade Multimedia, 1999. 4 : Vol. V. pp. 8-14. 200

PAGE 211

201 Webb Jeffery B Mosquitofish (Gambusia affini s & G. holbrooki) [Report]. Columbus : United States Geological Survey, 1999. Wheaton Fredrick W Aquacultural Engineering [Book]. New York : John Wiley & Sons, Inc., 1993. Wilson Geoff Aquaponics Proves Profitable in Australia: Barramundi and Lettuce Combination Increases Rev enues [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multim edia, 2002. 1 : Vol. VI. pp. 8-13. Xiangfdu Song [et al.] Study of Surface Aquaponics in Natural Waters [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2000. 3 : Vol. IV. pp. 16-20. Xiangfu Song [et al.] Study of Surface Aquaponics in Unison with Aquaculture [Journal] // Aquaponics Journal. Mariposa : Nelson/Pade Multimedia, 2000. 3 : Vol. IV. pp. 21-25.