The Importance of Bio-filtration in Aquaponics
Filtration is probably one of the most important “life supporting” part of your aquaponics system. By now you probably already know how how to check your ammonia and nitrite concentration in your water. Well, what makes all the difference and keeps things in balance is your bio-filtration setup. I started out with not really having one at all. I always thought that it was sufficient to pump the water through my grow media once in a while. Well, as my fish were growing, I kept wondering why they are all hanging out on the surface, gasping for air. I had installed an aeration pump to oxygenate the water. Well, when I checked my water chemistry to find out what was going on, I noticed an unhealthy concentration of ammonia and nitrites in my water. Both were about 1.5ppm, which is causing a lot of stress for the fish and can actually kill them. I then started thinking about all the fish waste and noticed that a lot of it was floating around like noodles in a soup. I decided to install a swirl filter to remove the solids. This helped a little. I would drain the collected solids once a week and it was quite a bit – and the smell – let me tell you! It is a great fertilizer for your other plants in your garden, if you have one.
Well, after a while I still noticed that my fish – about 47 Tilapia fingerlings were still stressed, gasping for air. I started thinking more about my nitrate cycle and did some more research about this. Then it dawned on me, my available bio-surface area was insufficient. The bio-surface area is the total area in your system on which beneficial bacteria can grow and convert ammonia to nitrites and then to nitrates. With that many fish and only cycling my system every three hours through my grow media, it wasn’t enough. I decided to add a large plastic box with bacteria friendly material in order to create a lot more bio-surface area for these little guys. I didn’t want to spend hundreds of dollars, so I went to a hobby and craft store and bought some Polyester bedding material. After a few weeks, things were stabilizing. However, I also noticed that my system was a bit unstable. Every time I fed the fish 3-4 times a day, my nitrite was spiking. I concluded that I still didn’t have enough available bio-surface area. I ended up exchanging my Polyester material with real bio-filter material. You get what you pay for.
Just recently I came across an article that was discussing moving bed filters with Hel-X filter material. I took a photo of a few of these Hel-X pebbles. They have a very intricate shape and a helix running on the outside to increase surface area, flow and their movement.