About once a month I once paid a visit to a couple that live about twenty minutes from me. One day they discussed with me their new found interest in aquaponics.¹
I received a royal tour of the greenhouse, which holds a basin for fish, pumps, tubs, tubing, gravel beds, and filters. I was favorably impressed!
One Man’s Poison
Fish produce body wastes. The word wastes in this instance can be changed to treasure, as the fish wastes serve as food for the plants. The waste water is pumped through plastic piping above tubs of pea gravel, in which the plants are rooted, free of soil.
The piping has small holes. This sprinkles the plants with the nutrient-containing water. The plants, even when small, yield an amazing crop. The couple’s bell pepper plants, though less than a foot tall, carried full-size fruits!
Usually plants do not prosper in fish waste; however, bacteria can and does alter that. The ammonia (NH₃), from the fish, is changed by nitrosomonas bacteria into nitrites (NO₂ˉ). Now nitrites in as such are not beneficial to plant or fish! However, Nitrospira bacteria take it a step further, oxidizing nitrites into nitrates (NO₃ˉ).
This is just what the plants need, nitrates. Some suggest that in addition seaweed extract should occasionally be added. Others suggest trace metals, such as iron. Mineral supplements are available, but may not be necessary, especially after the first year of operation.
2 is Better Than 1 – Aquaponics
What are some of the benefits of aquaponics? The water the fish are in does not need frequent change; only a little needs to be replaced because of evaporation. The water the plants receive is not contaminated by fertilizers or herbicides. No weeds can grow where there is no soil! The fresh-water tilapia fish prosper under conditions most fish do not well tolerate. In terms of maximum efficiency and minimum pollution, raising fish and plants together can’t be beat.
¹ Aquaponics is derived from aquaculture and hydroponics. The first term refers to the raising of fish, the second to the growing of plants in an aqueous medium.