My Interest in Aquaponics...
My interest in aquaculture and aquaponics started when I was a young boy. I had aquariums all over the house full of various kinds of tropical fish. My mother wanted to use dechlorinated water for her house plants, she reasoned that my aquarium water had no chlorine and that it may have some helpful nutrients. The results were unusually wonderful growth and absolutely beautiful houseplants.

In the mid 80s, our plastics fabrication company began investigating aquaculture as a potential market for our products.  As we looked at the aquaculture industry, it became apparent that plastics and aquaculture was a natural match.  With our core strengths in plastics fabrication, one of the nice advantages in developing our systems was the ability to quickly modify the plastic products we were working with. This helped accelerate our research and development. Working with several different kinds of liner material, it was recognized that the PVC material fit several applications for welded liners. We have used PVC successfully for many different kinds of tank liners including large round structures, special pond floating containers for fish, raceways, floating ocean mesacism containers for raising  Lin Cod fry, and various other functions.  We also use tough woven Polyethylene (PE) liner material for raceways, growbeds and ponds.  This PE is a good alternative to the very expensive EPDM.  Our welding capabilities allow us to weld rigid PVC into various shapes for use throughout our system. One of our areas of emphasis is manufacturing small recirculating systems, which can be used by schools and small commercial growers. These systems have been to optimized and improved upon for the easy of the user. These systems are highly efficient, easy to operate and clean and built to meet the growth, available area and budget specific to the user.

In the early stages of our Aquaculture program, a friend would bring us houseplants that she seemed to kill very quickly by watering her plants with her municipal water source. The first one she brought was a dried up, half dead Philadendrium. Just for the fun of it, we put it in the fish house and hung it above one of the tanks. Several times a day we would fill the pot with fish water and let the excess drip back into the tank. In less than one week we saw dramatic improvement and, in fact, the plant grew so well that it nearly took over the fish house! Many of the people who came to visit our facility would ask for a cutting of the monster Philadendrium because they thought it was a special plant.

Developing a System...
In the early 90s we began working with High Schools assisting them in starting their aquaculture, and later, their aquaponics programs. There has been renewed interest in the high schools agricultural programs because teachers can do everything with an aquaponics program that can be done with traditional agriculture with the advantage of being able to do it in the classroom. Urban dwellers areas can have their own “farm” and produce high quality protein and vegetables in a very small space. Both the urban and rural students learn a responsible form of agriculture that does have less impact on our environment.

While developing a system for aquaponics we have tried a number of different methods and configurations. Many of them work well but there are a few features we feel work the best and provide the most efficient operation and lowest initial investment. The first component to a successful aquaponics system is a solid, stand-alone aquaculture system that is easy to clean and maintain. An aquaculture system should be able to grow fish at close to 1/2 pound per gallon of culture tank water. By having these kinds of fish populations there are tremendous nutrients produced by the fish. In the aquaculture system there should also be an efficient way of removing the solids from the system. These solids may be utilized outside a flow through aquaponic system. An outdoors garden or compost pile are good places for this nutrient rich water.  

When the fish are fed they produce ammonia which is toxic to the fish, especially in its unionized form. Beneficial Nitrosamonas Bacteria convert the ammonia to nitrites, which are also toxic to fish and can cause brown blood disease. Another beneficial bacteria, Nitrobacter, then convert the nitrites to nitrates. In an aquaculture system, nitrates will continually build up, but most fish can tolerate high concentrations of nitrates. The wonderful news about fish water that is high in nitrates is that this nitrogen source is very available to plants.

The System...
After experimenting with several different plants growing methods we have chosen flow through grow beds design because of their simplicity and economics. A large part of the growbed can be assembled on site using local materials. As a base, plywood sheets (4' x 8' x 3/4") work well. For the sides, you can use 2" x 6" lumber for perlite beds and for a float system you can use 2" X 12". Depending on available space, you can work out the exact length.   You can also use concrete if you have the room.

To hold the water in the bed, use a high quality Polyethylene or fish grade PVC liner. These materials are tough and well suited for the job. You can place these growbeds on a table or they can be on the floor depending on the size and weight. You will have to make sure that when the water exits the growbed that the debris does not go back into the fish culture tank. Course perlite or rockwool are good growing medium. They are light weight and can be changed periodically.  Gravel or sand can be used but we have found that your production will increase when you remove the gravel or sand and use the following methods described.  We recommend that the plumbing that is used is large enough and designed to be able to clean regularly.   Aquaculture water will develop a substance called flock. It is a by-product of a good beneficial bacteria population and it is a good sign but it can clog plumbing when the fish populations are high.

Three Growbed Designs...
We have established three different growbed designs that have worked well for us. All three worked and were good for different plants. In the first design, the water from the fish tank was directed through the bed filled with perlite where the plants grow.  The water flows through the bed slowly to a sump tank or a pump where it is returned to the culture tanks. This worked very well and provides a lot of additional bio-filtration for the culture tank, giving the water more denitrification, degassing, and oxygenation as it goes through the growbeds and back to the tank.  Chives, Swiss chard, lettuce, etc. does every well in this system.

We also set up growbeds that we use floats with holes in them. We put the seedlings in net pots and put them in the holes. The water is about 10" deep, is directed through the grow beds and then back to the culture tanks. The water in this system should be kept aerated. The roots of the plants grow right in the water and we experienced tremendous root development with this method. Lettuce, basil and the like do very well in this system.

In the third design, the water is directed to another tank that is designed to make the water go anaerobic briefly.  This process is called a mineralization process and reduces the Nitrates and increases the availability of the trace minerals. This water is then aerated and sent through a grow bed or garden and is a tremendous source of nutrients for fruiting plants such as tomatoes, peppers and cucumbers.

What We’ve Grown...
With the growbeds we described, we have successfully grown a number of plants and herbs, including 4 varieties of basil, 6 varieties of leaf lettuce, chives, parsley, and Swiss chard. We also had great results with about 20 different ornamental plants including marigolds, zinnias, and citronella. Flowering plants such as tomatoes, cucumbers and peppers do well with the mineralization process. GG

Myles Harston is the owner of AquaRanch Industries, which specializes in the education of the user in the areas of science, hands on applications, marketing of Aquaculture and Aquaponic products.  He conducts workshops, speaks at agriculture conferences and works one on one to make new farmers entry into the world of Aquaponics a positive and profitable endeavor. He may be contacted at 815.796.2978, This e-mail address is being protected from spam bots, you need JavaScript enabled to view it or you can visit their website at www.aquaranch.com .