2011 Aquaponics Short Course – April 2011
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Table of Contents:
1. Overview of aquaponics...... 2
2. Water chemistry ...... 3
a. pH
b. Conductivity
c. Dissolved solids
d. Suspended solids
e. Oxygen
3. Nitrogen cycle...... 4
a. Ammonia
b. Nitrite
c. Nitrate
d. De-nitrification
4. Tilapia and other fish in the system...... 5
a. catfish
b. koi
c. Yellow perch and bluegills
5. Fish feed as nutrient sources...... 5
a. Proteins and Nitrogen
b. Phosphates
c. Potassium
d. Mineral premixes and micronutrients
6. Organic micronutrients...... 6
a. Chelated compounds
7. System design...... 6
a. Recirculating aquaculture
b. Greenhouse design and operation
8. Suppliers and vendors for equipment...... 9
a. Greenhouses
b. Vendors
Aquatic Eco-Systems
9. Bibliography...... 10
1. Overview of Aquaponics
The concept of aquaponics is to integrate the advantages of two of the fastest growing sectors of global agriculture. Aquaculture has proven to be much more efficient at producing food fish than hunting and gathering from inland lakes and streams or from the ocean. With high costs of fuel, labor, insurance, and dock fees, domesticated aquatic animals and plants are rapidly capturing the marketfor seafood and wild stocks of fish are increasingly being reserved for sport fishing. Meanwhile, controlled environment agriculture (greenhouses) and especially hydroponic production, is becoming a more important source of high quality produce. Concerns over water efficiency, biosecurity, use of pesticides, food miles, local production, and demand for more fresh vegetables are driving the rapid growth of these technologies. By integrating aquaculture and hydroponics, we believe we can address some of the weakness of each technology. For example, if not disposed of correctly, the effluents from fish farms can contribute to pollution and eutrophication of the receiving waters. While in hydroponics, two of the major expenses are for fertilizers and water. By taking the nutrient rich effluent water from fish culture, the hydroponics avoids two of the major expenses. As the plants absorb the dissolved carbon dioxide, nitrogen, phosphates, and micronutrients, the water is filtered and re-oxygenated and can be returned to the fish tanks for re-use.
Fig. 1. Illustration of enclosed re-circulating integrated aquaculture system. Water effluent from fish tank is pumped through plant beds and water collected at the terminal end of plant beds is pumped back to fish tank.
The basic design of the system is open to plenty of customization with various intermediate filter systems, additional lighting for plants, monitoring and control equipment and devices, pumps, blowers, emergency oxygen, and doors and screens, covers and movable walls and roofs. The following chapters will provide a short overview of aquaponics and the basic concepts and operations that one will need to understand before embarking on an aquaponics system for educational, home production or commercial endeavor. There are a number of more complete references and guidebooks and we strongly encourage those considering aquaponics to continue reading and digesting these works in addition to this short introductory workshop.
2. Water Chemistry
The water used for aquaculture and hydroponics is obviously the single most important factor in either production cycle. In general any water that is suitable for people to drink will be acceptable for starting an aquaponics system. Some time may be needed to dissipate any residual chlorine but typically 24 to 48 hour will suffice. After that, we tend to start with adding fish first as the waste from the fish needs to accumulate so that they are nutrients available for the plants when they are added. Thus the measurements of the characteristics of the water are very important.
pH – is a measure of the H+ (hydrogen ions in the water) pH level of the water is a measure of the acidity and alkalinity. Fish are somewhat tolerant of pH level so long as it stays near a neutral level.Some fish prefer slightly higher or lower levels but most dislike rapid changes in the pH. More important is the pH level for the hydroponically grown plants. The pH of the water will have a direct effect on the ability of plants to absorb certain nutrients dissolved in that water. In general, slightly acidic water in the range of 6.5 to 7.0 is more beneficial for most hydroponic plants. This is because the nutrient ions are more available to the plant roots in this range.
Conductivity – is a measure of the ability of the water to transmit electricity. Basically, any number of materials in water, make the water more capable of passing a current from a positively charged surface to a negatively charged surface. These may include salts, organic compounds, clay and silt, and even organisms like algae and bacteria. We use this as a shortcut to estimating the total amount of salts and other charged compounds that are in the water. Conductivity meters are inexpensive devices that quickly determine how well a current passes through a water sample. These provide the farmer with a quick estimate of the total amount of nutrients that are in the water and available to the plants.
Dissolved solids – is a more exact measure of the compounds which actually do dissolve in water. Many of the important nutrients for plants are salts which disassociate into cations and anions in the water. In aquaponics many of the anions and cations are released into the water from the metabolic wastes of fish.
Suspended solids – are the items that do not dissolve in the water but also do not settle to the bottom of the water column. These can include particles of feed and feces, algae, bacteria, and other items with a specific density close to that of water. These are important to manage as they can impact oxygen demand, may harbor deleterious bacteria or pathogens or pests. They may also include beneficial bacteria, provide needed nutrients to fish and/or plants, and support needed microbial populations.
Oxygen – is needed by both fish and plants. Fish obviously need dissolved oxygen in the water for their respiration. Levels of 3-7mg/l, or 3 to 7 ppm are best for fish. Plants also need oxygen in the water bathing the roots. Approximately the same levels are required. Plants constantly respire just as animals do, but during daylight hours they produce an excess of oxygen from the leaves, thus producing a net positive amount of oxygen.
3. Nitrogen Cycle
Ammonia – As fish break down proteins in their diet, their urinary waste is released as ammonia or urea, which immediately disassociates into ammonia. Ammonia in water is in ionized and unionized forms (NH3 and NH4OH) that have different toxicities to fish. The relative concentration of the forms is a function of pH and temperature. The ammonia and ammonium can be used directly by some plants. But in most aquaponics systems we utilize biofiltration with nitrifying bacteria to convert ammonia to nitrite and then nitrate. This is accomplished by naturally occurring bacteria which convert ammonia to nitrite. The bacteria require dissolved oxygen in the water to accomplish the nitrification.
Nitrite – Is an intermediate from of nitrogen (NO2) that is generated as Nitrosomonas bacteria oxidize ammonia and ammonium. Nitrosomonas oxidize ammonia compounds to gain energy, just as we oxidize carbon compounds for energy. Nitrites are very toxic to fish and in very small concentrations will cause brown blood syndrome and eventual mortality. Some plants are capable of utilizing nitrite directly, but most prefer the more stable nitrate form of nitrogen
Nitrate - or NO3, is produced from nitrite by another group of nitrifying bacteria, the Nitrobacter. Again these bacteria oxidize the nitrogen compound as “food”. However, nitrate is relatively benign for fish and one of the preferred forms of nitrogen for most plants.
De-nitrification – In the absence of oxygen, de-nitrifying bacteria are capable of converting nitrates to elemental nitrogen (N2 gas). The nitrogen gas then escapes back to the atmosphere.
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4. Tilapia and other fish in the system
Tilapia tend to be the fish of choice in most aquaponics systems. Tilapia are exceptionally hardy and grow well in high density systems. The market for live tilapia is strong nationwide and at the high density grown in most systems, they produce large amounts of effluent that can be used to support plant growth. Tilapia used in aquaculture are typically one of three species or a hybrid strain derived from the three species. These include the Nile Tilapia (Oreochromis niloticus) the Blue Tilapia (O. aureus) and the Mossambique Tilapia (O. mossambicus). Most of the red strains of tilapia are examples of fertile hybrids between various combinations of the three species. Tilapia are tropical fishes and in some systems the temperatures required for tilapia are too high for some of the plants to grown. In those cases, other species can be reared.
The Channel catfish, (Ictalurus punctatus) is used in some aquaponics systems. They grow well at temperatures slightly below those for tilapia. Catfish cannot be grown at densities as high as tilapia, but they have a good market price in most parts of the US.
Koi, are ornamental carps that have been selectively bred for hundreds of years in Japan, Korea and China. Their popularity has grown in the US and there are numerous koi clubs around the country. Koi will grow well at temperatures slight lower than those for tilapia and channel catfish. Koi can grow at fairly high densities as long as water quality in not degraded.
Yellow perch and bluegills have been grown in recirculating systems in the US Midwest and can be utilized in aquaponics systems. The marketability is regional. They will not grow at the densities that can be achieved with tilapia, koi or catfish.
Rainbow trout have been used in some aquaponics systems in higher latitude locations with very cool water supplies, 55- 60 degrees F. There are only a few plants that will grow well at these cooler temperatures, but several groups have grown water cress and cooler temperature varieties of lettuce.
5. Fish feed as nutrient sources
The basic driver of both fish growth and plant growth is the feed provided to the fish. In fact, density or number of fish is really less important to the functioning of an aquaponics system than the amount of feed input daily. The nitrogen dynamics of the aquaponics system has been a primary focus of research as the protein levels and subsequent nitrate levels are critical for the growth of the fish and plants respectively. In addition to the nitrogenous compounds, the fish and plants also require phosphorus. In fish diets this can be provided by ingredients including fish meal, meat and bone meal, feather meal or mineral forms including di-calcium phosphate, or Triple Phos.
Also important are the micronutrients. For fish these are usually provided by the vitamin and mineral premixes that are added into the diet formulation. These are typically added in excess to ensure that there none are limiting the growth of the fish. In aquaponics this is fortunate, as many of these same minerals are required by the plants. One of the most common limiting nutrients is iron. Fish require a relatively small amount of iron, but then tend to retain what they do ingest and so there is not much in the effluent stream. At the same time, iron is a critical micronutrient for plants and we frequently observe deficiencies in aquaponics operations. Luckily this can normally be solved by simply adding a few rusty nails to the system as a slow release form of iron. For rapid release, rusty steel wool can be added.
6. Organic micronutrients
If the practitioner desires to maintain an organic status for the vegetables, there are approved nutrients amendments available on the market.
7. System design
Fish - tanks versus raceways. Aquaculturalists are fairly evenly divided regarding the benefits of tank culture and raceway culture. And some fall neatly in the middle supporting hybrid systems with center divided raceways with rounded ends. In essence, any system will work to rear the fish and the preference of the fish farmer can be indulged. Normally the waste from the fish tanks then goes to a settling mechanism and biofilter. This allows the most dense solids to be removed while the biofilter converts ammonia compounds to nitrates. Water can then be delivered to the plants
Traditional Hydroponic Techniques
Deep Flow Technique
Gravel Bed Technique
Nutrient Film Technique
8. Suppliers and vendors
Aquatic Eco-Systems
Biomin
IBG
Nelson and Pade
Graingers
S7S Aquaponics
9. Bibliography
Bolivar, R., Mair, G. and Fitzsimmons, K. 2004. New Dimensions in Farmed Tilapia: Proceedings of the Sixth International Symposium on Tilapia in Aquaculture. Editors: American Tilapia Association, Aquaculture CRSP, and Ministry of Agriculture, Philippines. Manila. 854pp.
Brown, J.J., Glenn, E.P., Fitzsimmons, K.M., Smith, S.E. 1999. Halophytes for the treatment of saline aquaculture effluent. Aquaculture. 175: 255-268.
Chimits, P. 1975. Tilapia in ancient Egypt. Food and Agriculture Organization Report. 10: 211-215.
Chung, I., Kang, Y.H., Yarish, C., Kraemer, G.P., Lee, J. 2002. Application of seaweed cultivation to the bioremediation of nutrient-rich effluent. Algae. 17: 187–194.
Contreras-Sanchez, W. and Fitzsimmons, K. 2006 eds. Tilapia, Sustainable Aquaculture from the new Millennium - Proceedings of the Seventh International Symposium on Tilapia in Aquaculture. American Tilapia Association, Aquaculture CRSP. Veraruz, Mexico. 389pp.
Costa-Pierce, B.A. 1987. Aquaculture in ancient Hawaii. Integrated farming systems included massive freshwater and seawater fish ponds. BioScience. 37: 320-331
Costa-Pierce, B.A. 1998. Preliminary investigation of an integrated-aquaculture ecosystem using tertiary-treated municipal wastewater in Los Angeles, California. Ecological Engineering. 10: 341-354.
Edwards, P., Pullin, R.S.V. Gartner, J.A. 1988. Research and education for the development of integrated crop–livestock–fish farming systems in the tropics. In: ICLARM Studies and Reviews vol. 16, International Center for Living Aquatic Resources Management, Manila p. 53.
Ervik, A. Hansen, P.K., Aure, J., Stigebrandt, A., Johannessen, P., Jahnsen, T. 1997. Regulating the local environmental impact of intensive marine fish farming. I. The concept of the MOM system (Modelling-Ongrowing fish farms-Monitoring, Aquaculture 158: 85-94.
Elghobashy, H., Fitzsimmons, K. and Diab, A.S. 2008. (eds) From the Pharaohs to the Future: Proceedings of the Eighth International Symposium on Tilapia in Aquaculture. Egypt Ministry of Agriculture, ISBN 978-1-888807-18-9. Cairo, Egypt, 1447pp.
Fitzsimmons, K. and Carvalho, J. 2000. Tilapia Aquaculture in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture. Editors, Ministry of Agriculture, Brazil and Aquaculture CRSP. Rio de Janeiro. 682 pp.
Fitzsimmons, K. 1997. Tilapia Aquaculture: Proceedings of the Fourth International Symposium on Tilapia in Aquaculture. Editor. Northeast Regional Agricultural Engineering Service Publication No. NRAES - 106. Ithaca, N. Y. 808pp.
Hargreaves, J.A. 1998. Nitrogen biogeochemistry of aquaculture ponds. Aquaculture 166: 181-212.
Lockett, J. 2003. Polyculture: profiting from an eco-friendly mix. Atlantic Business Journal.14: 52–55.
Morrison, C., Fitzsimmons, K. and J.R. Wright 2006. Atlas of Tilapia Histology. World Aquaculture Society, Baton Rouge, LA. 96pp.
Nelson, R. and Pade. Aquaponics Journal.
Rakocy, J.E. 1997. Integrating tilapia culture with vegetable hydroponics in recirculating systems. In: B.A. Costa-Pierce and J.E. Rakocy, Editors, Tilapia Aquaculture in the Americas vol. 1. World Aquaculture Society, Baton Rouge, LA. pp. 163–184.
Rakocy, J.E. 1999a. Aquaculture engineering: the status of aquaponics: Part 1. Aquaculture magazine. July/August. pp. 83–88.
Rakocy, J.E. 1999b. Aquaculture engineering: the status of aquaponics: Part 2. Aquaculture magazine. September/October. pp. 64–70.
Rakocy, J.E. Donald S. Bailey, R. Charlie Shultz and Eric S. Thoman 2004. Update on tilapia and vegetable production in the UVI aquaponic system. ag.arizona.edu/azaqua/ista/ista6/ista6web/pdf/676.pdf
Timmons, M.B. and Ebling, J.M. 2007. Recirculating Aquaculture, 2nd Edition. 975 pages Publisher: Cayuga Aqua Ventures.
Tilapia: Biology, Culture, and Nutrition is essential reading for aquaculturists, nutritionists, geneticists, hatchery managers, feed formulators, feed mill operators, extension specialists, tilapia growers, fish farmers/producers, educators, disease specialists, aquaculture veterinarians, policy makers, educators, and students. Edited By: Chhorn Lim and Carl D. Webster. 2006 Softcover, 678 pages
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