some LFS sell the black foam for sponge filters in bulk that you can cut to the size you need. you can buy the ATI Hydro V kit, for $10 from http://www.americanaquariumproducts.com/index.html and for $2 more you can get the hydro V pro that has the black sponge that i like best.GolemGolem;4713337; said:I've been wanting to do a couple sponge filters (power goes out fairly often, my corries like to spawn right after this, want to save some cory fry) I think since I'm poor, but I have spare tubing and air pumps I'm just gonna make my own, is their any type of sponge that I SHOULD NOT use?