Great thread...lots of cool photos and interesting bits of information.
I am thinking I might change the filter on mine as well but I am a total noob and have no real clue what I am doing.
I understand the ceramic rings (like Fluval SPEC biomax??) are the biological filter and the foam is the mechanical filter? What kind of foam did you use?
Also, nice idea with the holes drilled into the filter box area....wish I had thought of that before I got mine all filled.