Topic/Paper # 1 - Introduction to Aquaponics

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1 Aquaponics Papers by Rebecca L Nelson Nelson/Pade Multimedia Aquaponics Journal PO Box 1848, Mariposa, CA Tel: nelson@aquaponics.com Web: Topic/Paper # 1 - Introduction to Aquaponics Aquaponics is the combination of recirculating aquaculture and hydroponics. Recirculating aquaculture is an intensive method of fish farming in which fish are densely stocked in tanks. The water in the tanks quickly becomes fouled as the fish eat and digest their food and excrete waste. Highly efficient filtration systems are used to remove the nutrient-rich fish waste and maintain acceptable water quality. Hydroponics is an efficient method of farming that uses soiless-growing systems to grow many types of plant crops. The plants are fed a solution of water and all of the essential nutrients. This precise blend is fed directly to the plant roots, allowing the plant to develop faster, healthier and with less labor for the farmer. In aquaponics, the fish waste provides a food source for the growing plants and the plants provide a natural filter for the water the fish live in. This creates a mini ecosystem where both plants and fish can thrive. Aquaponics is the ideal answer to a fish farmer s problem of disposing of nutrient rich water and a hydroponic grower's need for nutrient rich water. The key to a successful aquaponic system is a healthy colony of beneficial bacteria. These bacteria convert ammonia and nitrite into nitrate which is used by plants as they grow. Without the bacteria, ammonia and nitrite levels, which are toxic to fish and plants, would quickly rise. Aquaponics, aquaculture and hydroponics can all be used to produce large quantities of food in very small spaces in an environmentally friendly way. Advantages of Aquaponics: The combination of aquaculture and hydroponics is quite new and the potential for using aquaponics to grow high quality food around the world is tremendous. Here are some of the many advantages of aquaponic food production: Aquaponics utilizes the nutrient rich water from aquaculture that otherwise would have been a waste product or would need to be filtered in a more costly manner.

2 Aquaponics eliminates the cost and time involved with mixing traditional hydroponic nutrients. Aquaponics provides a truly organic, natural form of nutrients for the plants. By eliminating the soil in vegetable production, you eliminate all soil borne disease. Aquaponics uses a fraction of the water that traditional field production does because no water is wasted or consumed by weeds. In aquaponics, plant spacing can be very intensive, allowing you to grow more plants in a given space. With high stocking densities in the fish tank, plants will quickly grow and develop in an aquaponic system. In aquaponics there cannot be any pesticides or herbicides used, making the end product healthier and safer. If your climate permits or if you are growing in a greenhouse, you can grow crops in an aquaponic system year-round. Disadvantages aquaponics: The technology of combing hydroponics and aquaculture is very new and, although it is a fantastic method of producing food crops in a recirculating system, there are some problems inherent to combining these two technologies. Fortunately, as research continues and more commercial operations are established, these issues should be reduced or eliminated. Combining these two hybrid systems increases the potential for problems. Available nutrients are dependant on the number of fish, the size of the fish and the amount they are fed. Fish are very sensitive to pesticides, cleaning agents and chemicals so the only practical method of pest management is by using barriers and biological controls. This is an advantage as well because many consumers want pesticide-free produce. There is a compromise in ph most fish do best at but most plants do best at , the nitrifying bacteria do best at 7.0. The compromise for the optimal production in aquaponics is 7.0, neutral. The combination of nutrient-rich water and sunlight creates algae, which can clog pipes and drains.

3 History and Applications of Aquaponics Traditionally, aquaculture was done in large ponds but, in the past 25 years much research and progress has been made in recirculating aquaculture systems. The great benefit of recirculating systems is that you can grow up to 3/4 of a pound of fish per gallon of water. This means that large quantities of fish can be grown in a fraction of the space and water traditionally dedicated to aquaculture. The disadvantage of highly concentrated populations of fish is the large volume of wastewater that accumulates daily. Early on in research of recirculating aquaculture systems, experiments were done to determine the efficiency of aquatic plants in consuming the nutrients in this waste-water, therefore helping to purify the water for the fish in the system. As research continued, terrestrial plants were tested and proven to be an effective means of water purification for aquaculture and this nutrient rich water a nearly ideal hydroponic solution for growing plants. Lettuce, chives and other leafy crops were first considered for aquaponics but, more recently, commercial growers and researchers have great success with tomatoes, cucumbers, peppers, melons, flowers and many other crops. Research Research on aquaponics has been going on since the mid 1970 s and continues today. Most notably, the Agricultural Experiment Station at the University of the Virgin Islands, St. Croix, has earned world-wide recognition for over 20 plus years of work in refining commercial aquaponic systems. Other institutions where research on aquaponics have taken place include the Environmental Research Lab at the University of Arizona, Tucson, Oregon State University, Southern Illinois University, Auburn University, North Carolina State University, University of Washington, Texas A & M University, plus, NASA, the New Alchemy Institute, the Rodale Institute, the World Aquaculture Society and the American Society of Agricultural Engineers. New installations of aquaponic systems demonstrate that the interest in aquaponics is rising and educational institutions are eager to continue research. The Crop Diversification Center in Alberta, Canada has just completed the installation of a large aquaponic system and another, run by scientists from Rutgers University, was recently established at the Burlington County Research and Demonstration Greenhouse, in New Jersey.

4 Topic/Paper # 2 Hobby Aquaponics and Home Food Production Home Food Production: Aquaponics is an excellent means of growing food for anyone interested in fresh, pesticide free vegetables and fish for their family. An aquaponic system can be set up in a small greenhouse, garage, basement or backyard. Aquaponics in Education: Students of all ages can learn from an aquaponic system in which plants and fish live in a recirculating aquatic environment. A small aquaponic system can be set up in any classroom to encourage individual responsibility while demonstrating the principles of the nitrification cycle, plant usage of nutrients, ph relationships, botany, biology, chemistry, agriculture and business. In addition to classroom setups, an aquaponic system makes an ideal science or agriculture project for students. The monitoring and care of an aquaponic system by students inspires responsibility and creates excitement in the learning environment. A unit on aquaponics can be started at the beginning of a semester and run through the entire semester, allowing the educator to present the individual concepts and lessons as the plants and fish develop and grow. Hobby desktop On a hobby scale, aquaponics is catching on quickly. A home aquarium, with ornamental or food fish, can be combined with a mini garden, growing herbs, vegetables or flowers. A hobby system can be a beautiful showpiece and a food production system, all in one. Equipment and Designs Before covering specific system designs, we ll introduce the components that make up an aquaponic system. Not all components listed are used in every design. Fish tank Plant Grow Bed Biofilter Water Pump Aeration Clarifier Plumbing Tank heater or chillers Plant lighting Back up power and equipment

5 Greenhouse or other environmental protection System Designs Two basic concepts are emerging in aquaponic system design. One, which we ll call liquid-waste aquaponics, separates the solid waste from the system, using only the liquids. The other method, which we ll call total-waste aquaponics, uses all of the fish waste including the solids. In a liquid-waste system, the solids are removed using a clarifier or solids filter and can then be applied to soil crops providing valuable nutrients to those plants. This method is used in float and NFT systems, which you ll learn about later. The advantages of a liquid-waste system include a cleaner system and the use of the solid waste as a fertilizer for soil crops. In a total-waste system, all of the waste-laden water from the fish tank is pumped directly into the grow-bed, which is filled with some type of media such as gravel, sand or perlite. The biggest advantage to this system is that it eliminates the need to dispose or utilize the solids in another way. The disadvantage is that the solids tend to clog the grow-bed and plumbing, creating more labor for the farmer. With the increased awareness and interest in aquaponics, a few companies are now offering manufactured systems specifically designed for aquaponics. Up until recently, if you wanted to have a commercial or backyard aquaponic system, you had to build it. Since there are currently only a few ready-made systems on the market, it is likely that creative individuals will be hard at work designing and building other systems. It is these individuals, along with researchers and manufacturers that will be refining aquaponic technology in the next decade. The Media Filled-Bed system, the float system and the NFT or nutrient film technique are each variations of traditional hydroponic methods. When combined with a fish tank or tanks, each design can be applied to any application of aquaponics Media filled bed Float (raft) NFT Fish vs. Plant Ratios The biggest question in aquaponics is, how many plants can I grow if I have a certain number of fish? There isn t a simple answer to this question but there are some general guidelines. First, the number of plants you can grow is not just based on the number of fish or the size of those fish. The biggest determining factor is the amount of food added to the system. Plus, the equation varies depending on your application and the design and size of the system.

6 In media filled bed systems, there is a general formula, for every 1 cubic foot of water in the fish tank you can accommodate 2 cubic feet of grow bed. This 1- to-2 formula also works for small hobby or desktop systems. The scientists at the University of the Virgin Islands have determined that it takes 57 grams of feed to support 1 square meter of lettuce in a float system. Given that you generally feed about 2% of total fish body weight per day, you can calculate the size of the float bed you can support. Nitrification Cycle There are essentially three crops in aquaponics the fish, the plants and the bacteria. More than 50% of the waste produced by fish is in the form of ammonia, secreted in the urine and, in small quantities, through the gills. The remainder of the waste, excreted as fecal matter, undergoes a process called mineralization which occurs when Heterotrophic bacteria consume fish waste, decaying plant matter and un-eaten food, converting all three to ammonia & other compounds. In sufficient quantities ammonia is toxic to plants and fish. Nitrifying bacteria convert ammonia first to nitrite and then to nitrate which plants consume. In an aquaponic system the nitrifying bacteria will thrive in the bio-filter, gravel, water and growing media. Most aquaculture suppliers and aquarium stores sell highly concentrated beneficial bacteria. Although it is not essential, it can provide a quick start to an aquaponic system. Topic/Paper # 3 Commercial Aquaponics Commercially, aquaponics is in its infancy but, as the technology develops and is refined, it has the potential to be a more efficient and space saving method of growing fish, vegetables and herbs. Although there are currently a limited number of commercial aquaponic operations, many people are expressing a strong interest in this intensive method of growing food. An aquaponic system isn t difficult to maintain but there are periodic tasks that must be done to ensure a healthy system. Fish Feeding The availability of dry, species-specific fish food is quite new and is the result of the rapidly growing aquaculture industry. Today s specialized fish feeds provide precise amounts of protein, carbohydrates, fats, vitamins and minerals. In a hobby or ornamental system it is fine to feed your fish only once a day. If food production is your goal, you ll want to maximize your efforts and feed more

7 frequently. Feeding by hand gives you the opportunity to observe the fish and their feeding habits. Many commercial growers will feed every couple of hours using a timed mechanical feeder or use an on-demand feeder so the fish can eat whenever they are hungry. Fish Care Every day you should visually inspect the fish and the system. Make sure the water is flowing properly, the aeration system is working and the drains are free of debris. Watch to see that the fish eat vigorously and swim normally. Look for problems such as fungus, open soars, torn fins or discoloration and check the temperature and ph of the water. Additionally, other water quality factorrs should be checked at least every week. These include ammonia nitrogen, nitrite nitrogen and dissolved oxygen. Fish Harvesting In a home food production system, you will most likely harvest fish as you want them, once they ve matured. Commercial operations will harvest based on market demand and production. Farm raised fish always taste the best if they ve been purged for several days prior to harvesting. Ideally, the fish should be removed from the main system and held without feed for several days prior to harvest. Water Quality Testing Ammonia Nitrite Nitrate PH Temperature Dissolved Oxygen Alkalinity Cleaning Filters and System The key to a healthy system is keeping it clean, removing any dead or unhealthy plants or fish, maintaining filters and emptying the clarifier if you are using one. Plant Seeding, Rotation and Harvesting When growing leafy crops that quickly mature, such as lettuce and herbs, you should plant frequently so you are assured of a continual harvest. Indeterminate varieties of many long term crops, tomatoes and melons, can produce for many months. Seeds for an aquaponic system are usually germinated in a small rockwool cube or in a container of loose perlite or vermiculite.

8 Germination can be done within the aquaponic system or in a separate area designed to provide proper environmental conditions for germination. Once the seed has germinated and a seedling has developed, the small plant is transplanted into the plant grow bed. Plant Health and Care In an aquaponic system, the nutrients available to the plant are directly proportional to the quantity of fish and the type and amount of food fed. The more precisely a plant's needs are met, the more vigorous the growth will be. When you observe a lush, healthy plant, you can be sure of its environmental and nutritional requirements are being met. As preventative care, you can send the fish tank water to a lab for nutrient analysis to help you determine what nutrients, if any, might be lacking. Concentration of Elements Many hydroponic formulas have been developed over the past 50 years, with some designed for specific plants, while others are designed for general hydroponic gardening. In an aquaponic system, you have the advantage of a built-in fertilizer source from the fish waste. The disadvantage comes from not having a precisely mixed formula. A well-balanced aquaponic system will support a variety of leafy crops and systems with high-density stocking of fish can support fruiting crops such as tomatoes and melons. Nutrient Deficiencies and Excesses Since there is no soil to act as a buffer, your aquaponic crops will quickly respond to a nutrient deficiency or toxicity. Nutrient deficiencies are more common than toxicities, with the most common deficiencies in an aquaponic system being potassium, calcium and iron. Without proper amounts of any of these elements, plant growth will suffer. If you have deficiency or toxicity, the plants will respond with symptoms such as discoloration of foliage, slowed growth or problems with fruit development. A minor deficiency or toxicity may not initially show symptoms, but eventually will affect plant growth, vigor or fruiting. If certain elements are determined to be deficient in an aquaponic system, they are sometimes added in very small quantities with no ill effects to the fish. Specifically, potassium and calcium are added in the form of potassium hydroxide and calcium hydroxide and iron is added in the form of chelated iron. These components will alter your ph and if added in too large of quantities can be toxic to the fish. Another option for supplementing the nutrients is to add some seaweed extracts or other mild organic fertilizer. Nutrient Testing

9 Test kits that measure various elements can be used to determine the concentration of the nutrients in your system. Many commercial growers test on a regular basis to ensure they are feeding an adequate diet for plant growth. Regular leaf analysis is another tool for determining the health of your plants. Leaf tissue samples are dried, crushed and analyzed to determine the exact nutrient content. In the event of a combination of nutrient deficiencies, the symptoms of one problem may mask the symptoms of another. A leaf tissue analysis may be the only way to determine what is happening. Fish and Plant Selection Fish Tilapia are commonly grown in aquaponics because they are very hardy, fast growing, easily bred and a popular food fish. They do well in water with a temperature in the low 70 s, which is compatible with most vegetable crops one would consider in an aquaponics system. Additionally, their tolerance to varying water quality conditions makes them an excellent option for aquaponic culture. Keep in mind that in some locations there are restrictions on non-native species so check with your local fisheries department to see what species are available and legal in your area. Other species you might consider include bass, crappies, sunfish, catfish, trout or other food fish and ornamental fish such as koi, goldfish and tropical aquarium fish. In deciding what fish to raise in your system, ask yourself these questions What water temperature can you maintain? What stocking density can your system support? What fish are available and allowed in your area? What fish do you like to eat if it is a home food production system and what fish you have a market for if it is a commercial system. What commercial fish feed is available to you? You can learn more about the individual needs of different species of fish from books on aquaculture, your fish supplier, local fisherman or fish farmers. Whatever fish you choose to raise in your aquaponics system, the role is the same the fish eat food, and excrete waste, which, with the help of beneficial bacteria, is broken down into elements that the plants consume.

10 Plants It used to be assumed that an aquaponic system could only support leafy crops like lettuce and herbs but in the past few years, aquaponics enthusiasts worldwide are all proving that assumption wrong. Researchers at the University of the Virgin Islands are growing tomatoes, melons, squash and flowers in addition to their leafy crops. Commercial growers have had success with cucumbers and bell peppers and hobbyists are raising many other traditional garden crops like strawberries, peas and beans. If you are just getting your system established and your fish biomass is not at its maximum, you might want to begin with leafy crops. Lettuce, spinach, basil, watercress, mint, chives and oregano all will thrive. Once your system is well established and you are nearing optimum stocking density, you can add fruiting crops like tomatoes and squash or whatever other crop that you like to eat or that you have a market for. Fish vs. Plant Ratios The biggest question in aquaponics is, how many plants can I grow if I have a certain number of fish? There isn t a simple answer to this question but there are some general guidelines. First, the number of plants you can grow is not just based on the number of fish or the size of those fish. The biggest determining factor is the amount of food added to the system. Plus, the equation varies depending on your application and the design and size of the system. In media filled bed systems, there is a general formula, for every 1 cubic foot of water in the fish tank you can accommodate 2 cubic feet of grow bed. This 1- to-2 formula also works for small hobby or desktop systems. The scientists at the University of the Virgin Islands have determined that it takes 57 grams of feed to support 1 square meter of lettuce in a float system. Given that you generally feed about 2% of total fish body weight per day, you can calculate the size of the float bed you can support. Examples of Commercial Operations Commercial Aquaponics systems are in operation in North American, Asia, Europe and Australia. Examples of commercial systems and their operations will be presented. Additional Information Sources: Following are sources for more information on aquaponics: Conferences, Courses: The University of the Virgin Islands offers an annual weeklong short course on aquaponics and recirculating aquaculture. This course, taught by the knowledgeable and experienced staff at the Agricultural Experiment

11 Station, takes place every summer at the UVI campus on the island of St. Croix. ( Science Alive is a conference with a focus on aquaponics, hydroponics and controlled environment agriculture for teachers, students and industry members. Science Alive takes place in Tucson, Arizona, offers a comprehensive and diverse program that anyone interested in this technology would find educational and fun. ( The Crop Diversification Center in Brooks, Alberta Canada offers periodic courses in aquaponics for both beginners and experienced growers. Aquaculture International offers aquaponics courses in North Carolina. ( Websites: Aquaponics.com, home of Aquaponics Journal, offers plentiful information on aquaponics plus has and videos, CD-Roms, books and school curriculums on these technologies for sale. ( The University of the Virgin Islands website provides lots of information on their aquaponic and recirculating aquaculture system designs. ( Future Aqua Farms has a website with many photos and information on their commercial aquaponic farm in Nova Scotia, Canada ( Cabbage Hill Farm in New York has a website that showcases their aquaponic greenhouse and includes how-to information on aquaponics ( Books, Curriculums Desktop Aquaponics is a booklet that provides step-by-step instruction for establishing and maintaining a desktop aquaponics system. You can learn more about it at aquaponics.com The Aquaponics Curriculum Package is for educators who want to use aquaponics as a teaching tool in their classroom. The basic package includes a teachers manual, students manual, color transparencies, a CD-Rom and a complimentary subscription to Aquaponics Journal You can learn more about it at aquaponics.com Introduction to Aquaponics Video and DVD -. You can learn more about it at aquaponics.com Recirculating Aquaculture Systems, 2 nd Edition is a comprehensive book on RAS technology and includes a lengthy and detailed chapter on aquaponics by Dr. James Rakocy. To purchase a copy, contact Dr. Rakocy ( jrakocy@uvi.edu).