IBC Aquaponics Update for Earth Day

Happy Day After Earth Day! Between work, an exciting HS soccer game, feeding the herd and working around the farm, there was just no time to add anything yesterday, but I am making up for it today.

One of the classes I attended at the SC Organic Growers Conference back in March was an Aquaponics "How To" class. During the class, I picked up a number of good pointers and things that I wanted/needed to change on our small aquaponics system that day. So, this year for Earth Day I updated our IBC Aquaponics system I built last year.

In the system I designed, our pump was always on and the growing bed was always filled with water. One of the things I learned in the class was that the water level needs to rise and fall. This is because there needs to be some level of oxygen in the growing medium for the health of the plants and to keep the stuff that gets trapped in the rocks from becoming a stinky, anaerobic mess. There are two good options for doing this; build a bell siphon or put a timer on the pump.

There are lots of resources for building a bell siphon. Here is a link to instructions on how to build one if you would like to try. If you do a Google search for bell siphon you will find thousands of great resources on how to make one. One day I might try to add one to the system but for now I took the easy route and added a timer. I chose a simple indoor timer (the pump plug is in our sun room) that I found at Walmart and set it to power the pump for an hour and turn off for an hour. This setting seems to be working well for now but I may make some changes to it once things get warmer.

The second addition I made to our aquaponics system is the addition of red wiggler worms to the growing medium. Apparently, no aquaponics system is complete without worms. They eat all the crud that gets added to the growing medium; fish poo, dead plant roots, bug pieces, etc. Occasionally a worm will fall into the tank below and provide some tasty protein for the fish. I only added a handful of worms to our system at first. I want to see how they do before I add more.

Worms are not affected by the water in the growing medium. They do not drown as I once thought they might. Worms conduct transpiration through their skin and can take in oxygen from water. Again, the trick is to let some oxygen in to the bed occasionally so they can breath.

This year I found a great local source of tilapia at Southland Fisheries and added 35 tilapia fingerlings to the tank instead of the goldfish we used last year. Tilapia are a good choice for a small aquaponics system for a number of reasons. First, they are fairly hardy fish and tolerate a wide range of water qualities. Second, they like and need warm water. This is especially important here in SC where it gets pretty darn warm in the summer. I should be able to keep the water in an acceptable range through the end of Oct which will give the fish plenty of time to grow.

Our final addition to the IBC Aquaponics system was to add some plants. Thirty-five fish will create a lot of waste that will need to be filtered out by the plants. We added a variety of lettuce, spinach and tomato plants to start with and I am looking forward to seeing them grow.

Just a word of caution on adding fish... Consider adding your fish gradually so you can condition the beneficial bacteria in the growing media. If you add too many fish at one time the waste they produce can overwhelm the nitrobacter in your system and the bacteria won't be able to handle the amount of nitrogen in the water. This can cause a major fish kill. Make sure to monitor the amount of nitrites and nitrates in the water and do a partial water change if it gets too high. You can get water test kits in any fish store. In our case, we kept goldfish in the tank all winter and added 10 tilapia about 2 weeks ago to get the nitrogen cycle started.

Well, that's it for this entry. If you have any questions about the things we did to our IBC Aquaponics system, please drop me a line. Happy Earth Day a day late!