since my filter is doing a poor job with its bio filtration, i thought about an in tank bio filter. check the picture for a general idea of how it looks.
the bio-ball-holder would be discuised as a log cabin with brown filter mesh at both ends. think it'll work?
If you are going to have submerged bio-media then you might as well have it in a canister outside the tank and save the tank room. Otherwise you could look at above tank wet/dry trickle which is excellent bio-filtration and hidden under the hood.