It is not just the holes but the sponge structure that keeps it from clogging. Swiss Tropicals in Ohio sells Poret open cell foam. This is the good stuff. It will last ten times as long as regular sponges, so the guys who pay one time are ending up paying less in the long run.shadowdrag0n said:i saw those too. and used them, but the clog up so eaisly. i was looking for something with bigger hole. anyone knows? :-?