I use 2 powerheads on 2 large sponges and a large Eheim canister on my 225g with 2 Jags and their brood...Just cover the intake of the canister with foam...they pretty much stay away from the intakes and the feed on the food that lodges in the sponges....joshee;4032340; said:also is a big sponge filter ok for sole filtration of a 4ft tank? im a bit scared of putting a powerhead or canister in at this stage, maybe a foam pad over the inlet?