That's interesting how you did the sponge in the Eheim HOB 100 filter!
I did something similar, but put a very coarse "pre-filter" bit of sponge inside the strainer part of the intake tube (to keep baby shrimp safe). I found it kept clogging up and needed frequent attention. It never occurred to me to just put a wad of sponge in place of the strainer part.
Are you using window light?
PS - I LOVE the Eheim HOB filters - built solid, very quiet, and easy to clean.
Last edited by Jane of Upton; 07-04-2010 at 04:52 AM.
Reason: added ps