For this year’s planting, I got some heirloom lettuce seeds to experiment with. We plan on having some lettuce in the fish tank as well as in an NFT system in the greenhouse; we will also have some growing in a soilless mix both inside and out. One of the things we like about aquaponics is the idea of being self sufficient: you can eat what you grow both plant and fish. For reasons that will be fully explored later, we will be limiting ourselves to using pet goldfish instead of something edible like tilapia. Materials listed in order used:
- Aquarium Starter Kit from Walmart ( tank, pump, fish food, water conditioner, filter)
- gravel 24″ curtain air stone
- single output air pump
- fish food
- 10 fish
- Lettuce started in grodan cubes and net pots
- Anti-fatigue mat
- fish net
- rain gutter screen
- 3″ drainage tube
- peat moss
Version 1: The anti-fatigue mat is used as a raft for the lettuce in the Grodan cube in the net pot. You can see the air hose right next to the thermometer The cat liked this version the best.
At this point it was decided that there were three problems with the initial system: The window did not get enough light to support the lettuce. The lettuce roots should not be exposed to light for best growth. The cat liked the water too much, we didn’t want to give him time to find out about the fish and how tasty they might be.
The solution was to put the tank in the bedroom in the eastern facing window (great white noise….), create a drainage tubing raft and build a net cage to protect the plants and fish from the cat. We made the rafts first:
Version 1.2: In the third picture you can see the duckbill we got from a local stream. The duckweed acts not only as a biofilter, but later on as food for the fish. You can see the air pump in the first picture on the right of the tank, with the clear hose going into the tank and the airstone, aerating the tank.
Here is the fishtank in it’s new location, notice the lettuce is no longer dependent on artificial light:
Version 2: The gutter guard keeps the cat out and still lets us feed the fish without taking off the cover. Can you see how the roots are poking out of the net pot?
These pictures were taken on March 23. The Duckweed has grown!!!! So has the lettuce!!!
As of this posting, we have three remaining fish, which is actually normal. The standard is to have about 1 goldfish for every 7 gallons of water. Some of the fish also had a fungus disease, one of the remaining three exhibits this fungus, it looks like salt crystals is clinging to him. Unfortunately we didn’t know how to inspect them when we originally got them, since it seems most have suffered with this problem since we got them.
You can see that the roots have explosive growth, coming out of the raft tunnels. The lettuce is also thriving, we often have to prop of the leaves from drooping into the water. The PPM has stayed remarkably low, our tap water comes in at about 190-230ppm so 250 is pretty good, with the number staying very constant.