5 WEEFTM 2013 Cartagena
structures enable bacterial growth that converts the ammonia species in the waste to nitrites and then nitrates, which is the food for the plants.
• The plants tank houses the plants with their roots hanging down into the water.
• In the sump pump tank, the water is pumped into the fish tank. Replacement water can be added in this tank to regulate the depth of water in the system.
Figures 3 and 4 show 3-D, cut-away, and cross-sectional views of the system.
The small aquaponics system was designed so that it could be assembled and disassembled easily with only bolts and nuts (no nails or screws). The boards are conventional pine 2x4, 2x6, and 2x8 lumber with a width of 1.5 in. (38 mm) Treated lumber was not considered because of the possibility that the chemical treatment would contact the water. The plants and sump pump tanks are formed by the pine boards. Five cm (2 in.) thick foam boards are placed against the pine boards, and then a food-grade EPDM (ethylene propylene diene monomer) liner is laid on top of the foam boards. The fish tank is a food-grade polyethylene tank. A high efficiency light is mounted above the plants tank to supplement natural light. The plumbing pipe and tubing is food-grade plastic.