Aquaponics Filtration:Mineralization and Biofilter Tanks

Image 11-28-17 at 5.01 PMThe new filtration is working out really well. As previously posted, the Settling Well is settling well! The next step in the filtration is a 50-gallon cone bottom tank to act as the mineralization tank filled with Kaldness media inside. Image 11-28-17 at 5.07 PM.jpgAbout 40% of the volume of the tank is filled with media. The Kaldness media provides a lot of surface area for bacteria to mineralize some of the solids that slip through the Settling Well. When redesigning the system, I wanted to use parts we already had on site. The cone bottom tank is perfect for this part of the filtration as it is easier to clean out than the 50-gallon barrels that we also have. Since this tank is static, it is cleaned out a lot more often than the biofilter, so I thought the cone bottom would be best for mineralization. The screened piping works great for the inlet and outlets. Image 11-28-17 at 4.58 PM (1)It is very important to close off the ends of the screen pipe so that the media doesn’t collect inside clogging the flow. When my mineralization tank started overflowing, this was the reason.  I used zip ties to close them off, but I’m sure there are other methods that would work just as well.There is an array of 6 airstones that is submerged all the way down to where the cone part starts toward the bottom of the tank. The airstone array helps agitate the media when it is time to clean out the tank every two weeks or so. Something I forgot to do before adding the media was add some sort of screened standpipe so when I drain the mineralization tank all of the media stays in the tank. For this purpose, I use some of the screen pipe as shown in the photo. When I am ready to drain the tank, I shove the screen pipe down into the drain at the bottom of the cone and it keeps the media from escaping. When I want to clean the tank, I open up the air to the airstones and let the turbulence bring most of the solids into suspension and then open the drain. After I put the screen pipe in of course! You only have to make that mistake once and then picking up a billion pieces of plastic starts drive the point home! In the future, I hope to connect this drain to another tank to keep the solids that drain out so that we can mineralize that material even more.

Following the mineralization tank is the biofilter. Using the same media, I filled it to about 60% volume. The biofilter is a 50-gallon barrel and is actively aerated with the same airstone array as the mineralization tank. Image 11-28-17 at 5.11 PMThe aeration helps to keep the media agitated, grinding whatever made it past the mineralization into finer suspended solids that eventually get consumed somewhere in the system by bacteria or something like the ostracods (seed shrimp) that inhabit the system.

From there, the water goes into the sump and out to the plants after going through a UV sterilizer to decouple the fish system from the vegetables.


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