We spent a little time re-configuring our experimental fish farm here at home, took a few photos and whacked up a video of the fish filters for home and how we use only venturis to aerate this system.  It has no air pump or air stones on it.  However it does have a small 20 liter per minute air pump we use when draining tanks or a tank is off-line for whatever reason.

The make up of the filtration unit is a Radial Flow Filter (RFF).  The RFF takes water only from the bottom outlet of the fish tanks, then onto the biological filter.  The main flow from the surface of the fish tanks goes directly to the biological filter.  Then they all meet up at the pump sump.

This little fish filter unit is simple and easy to build.  While we used expensive and nice looking drums, all of the filters can be made out of olive drums or the good ol’ blue drums.  The filtration has been set up to handle 4000 liters of fish tank.  In our fish farm at home, we only had room for 3 x 1000 liter fish tanks.  Not to be short changed we connected the waste from the Radial Flow Filter to our Earthan beds.