By April 2013 we will be putting tilapia fish into our aquaponics tanks. Right now the water temperature is 50 degrees F. Tilapia need 70 degrees or more to thrive.
Until then, there are three little gold fish swimming around. These little fellows were added to the water in the fall as pet store purchased feeder fish, 25 cents a piece. On introduction they were skinny and sickly, barely surviving. In fact 70% of the fish didn’t make it.
Now these remaining three are thriving and are 4 times the size. In fact the other day, I decided to plop a few small slugs (they are overrunning the place) into the fish tank. To my surprise the fish eat the slugs! Now we no longer have a slug problem, we have a fish deficiency.
With all of this being said, I actually ment to write about how the goldfish, and future tilapia will live. Along with food, like slugs, they need oxygen and filtered water to grow big and strong. Our goal being that the tilapia will eventually grow big enough for the diner table.
How do we keep the fish alive? Well, most closed aquaculture systems use pumps to move water around. In our case we use a small 500 gallons per hour 12v dc bilge pump. The pump is powered by a car battery calculated to hold enough juice for two cloudy days. Clouds, what do they have to do with anything?
The battery is charged by a 100 watt solar electric panel (clouds reduce the juice).
Other components, like a solar controller to regulate the solar electricity coming to and from the battery; a 24 hour timer (set to run the pump 15 minutes every hour) reduces the ware on the pump and slows the drain of the battery; and on/off switches and fuses; all help regulate/protect the flow of electricity in the system.
The water is pumped from the fish tank to another tank “up hill”. The up hill tank houses multiple species of edible plants, their roots grow down into the water providing biological filtration. The tank is also fairly still, so fish poop, dead leaves, and other gunk sinks to the bottom of this tank and becomes a benthic environment. Here beneficial photo and zooplankton thrive releasing important aquatic micronutrients into the system. The plankton and their larvae also become food for the larger animals in the system.
As the up hill tank fills up, it drains into a tank below it. This tank is empty of any animals at the moment. But, the plan is to try growing fresh water clams and lobsters in there. The clams help filter the water, and the crayfish are fed extra vegetation that we can’t eat.
The water flows from this tank, via gravity, into the first tank where the goldfish live. This tank is the one that will be home to blue tilapia in the spring.
I will post more details about the tilapia culture this coming spring.
Until then expect other interesting posts about our bioshelter’s inner workings!