Aquaponics:
Horticulture and the
Science
of Plants |
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 Overview of the aquaponic system. It is combination of a aquaculture fish tank and a hydroponic trough growing system. The bioreactor removes toxic levels of ammonia. Instead of pumping water directly out of the fish tank into the bioreactor, the water in collected in pump tank (a holding tank with a water pump), then pumped into the bioreactor; this facilitates settling and removal of solid fish waste. |
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80 gallon fish tank |
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The fish tank is connected to a holding tank by a pipe at the
bottom.
A water pump in the holding tank pumps the water up into the
bioreactor.
The bioreactor has return drain at the bottom. Valves can be used to divert the water back into the fish tank or to the hydroponic troughs. |
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The bioreactor is a bed of small gravel in a shallow
trough.
The water from the holding tank is distributed across the surface of the bioreactor by PVC pipe with holes drilled in the bottom side. In the bioreactor are two rushes and young chinese water spinach plants (kang kong). The plants are not necessary for the bioreactor, but it makes an excellent hydroponic growing bed. The plants absorb the extra nitrate nitrogen for their growth. |
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There are about 40 tilapia in the 80 gallons fish tank.
Tilapia
are a tropical fish that can only survive in warm water. They are
cichlids,
which means they raise their young in their mouths. All the fish
have been hormonally treated to be male, because male fish grow
faster.
The water has to be kept in the 80s and 90s for the fish to
flourish.
The the fish are fed twice per day with a tilapia food. The feeding rate is 5% of their body weight daily. The ammonia level is monitored in the fish tank. When
ammonia
nitrogen approaches toxic levels (2 ppm NH3-N) some of the water is
drained or
the
water pH must be adjusted. The nitrifying bacteria in the
bioreactor do an excellent job of keeping the ammonia levels low.
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