Originally Posted by aspects

if set up properly, your aquaclear HOB can get down almost to the micron level. i always suggest using a poly-fill or quilt batting in addition to the filter sponge. this fine mechanical media will help remove tiny particles from your tank.
also, you do not need carbon in your filter, at all. dont waste your time or money on it.

you are probably having circulation issues in yourt tank. because the slide (waterfall portion of your filter) is directly above the intake, it is pushing a lot of the particles away from the intake.
try putting the filter on one of the sides rather than the back, at least while it cycles.
also, the addition of a powerhead would help a lot.