Introduction: Building an Aquaponic System

Aquaponics is the combination of aquaculture and hydroponics. In aquaponics, the nutrient-rich water that results from raising fish provides a source of natural fertilizer for the growing plants. As the plants consume the nutrients, they help to purify the water that the fish live in. A natural microbial process keeps both the fish and plants healthy.

Step 1: Acquiring the Materials

To build this system you will need to construct two grow beds, two fish-food growing tanks, a fish tank, as well as a stand to elevate the fish food tanks.

To build the grow beds you will need:
5  8' 2x4s
1  4'x8' sheet of 1/2'' plywood
4  8' 4''x4'' posts
8  3/8'' carriage bolts with washers and nuts
555' sq. of pond liner
2'' deck screws
small grade pea gravel
2' permeable bags (coconut fiber bags and vermiculite)

To build the fish tank and fish-food tanks you will need:
2  55 gallon drums (plastic)
1  little giant 200gph submersible pump
2' sq. of metal mesh filter
8' of 3/4'' flex hose
small grade pea gravel
1  1'' 8' PVC pipe
6  PVC fittings
2  90 deg. PVC fittings
1  'T' PVC fitting

To build the stand you will need:
Scrap steel (we used 3'' steel pipe)
Spray paint

Step 2: Building the Grow Bed

Start by building two 8'x2'x8'' grow boxes with the 2''x4''s and plywood for the base. Line the entire inside with pond liner and fill with the pea gravel. Mount the beds on the 4''x4'' posts with the carriage bolts and position them on top of each other with easy access to both and ample spaces between them for plants to trellis and mature. DO NOT MOUNT THE BEDS FLAT. The beds must be mounted on angles (around 5 deg. from flat) to allow for the water to flow down them and back into the fish tank. The top bed should be higher towards the fish-food tanks; and the lower bed should be lower towards the fish tank.

Cut a hole in the bottom of the top bed (on the end that is angled down) for the 1'' PVC pipe to allow for the water to flow from the top bed to the bottom bed. Cut another hole in the side (although at the bottom) of the bottom bed for the 1'' PVC pipe to allow for the water to flow back into the fish tank.

Step 3: Building the Barrel Stand

One drum will be on the floor and on its side between the supports of the stand (this is the fish tank). Cut open the top to allow for oxidization of the tank. A simple wooden stand and legs can be built for this barrel to keep it from rolling over. The other barrel is cut in half to make two smaller ponds on top of the stand. This creates more surface area for growing duckweed and other plants that will feed the fish and clean the water. Cut a hole in the higher staggered barrel (about 3/4 of the way up) for a 1'' PVC to allow the water to flow into the second fish-food barrel. These barrels are staggered to allow for gravity flow. Put about 6'' of gravel in the lower barrel. Cut a hole about 3/4 of the way up in the lower barrel for a PVC pipe to let water flow into the top bed. On the end of this pipe attach the 'T' fitting and another pipe across. Drill some holes in this cross pipe and block the ends so the water can sprinkle down through the holes.

We made the stand from 3'' heavy duty steel pipe because we had it laying around, but something a little less heavy could be used. Bear in mind it has to support 55 gallons of water.

Step 4: Circulating the System

 Fill all three barrels with pond or rain water. Put the pump in the fish tank and connect the flex hose from the pump to the top fish-food barrel. Turn on the pump and start the flow. The water is going from the fish tank - into the top fish-food barrell - into the second fish-food barrel - into the top bed via the 'T' sprinkler - along the top bed and down into the bottom bed - out the bottom bed and back into the fish tank.

Step 5: Introducing the Elements

Introduce fish into the fish-tank, duckweed and algae into the top fish-food tank, snails and oxygenating plants (such as Elodea) into the lower fish-food tank, and plants you want to grow into the beds. Plant either in the permeable bags, or directly in the gravel depending on the plant species.

To control how much water goes into the beds - a timer can be used for the pump. A simple timer that plugs into the wall outlet can be used. How often you want the pump on depends of which plants you are planting and how much water they need.

Be sure to use fish that can eat what you provide. Obviously you cannot use carnivorous fish like trout. We have Rock Bass in our system.

Enjoy your fish and vegetables!

A simple filter can be constructed between to lower bed and the fish tank to take out soil and other solids that have made their way into the system.