I'm trying to find a large piece of foam/sponge - similar to the sponge blocks used in an AquaClear HOB. I need it to be about 2" thick, and 10" x 12" minimum. I've heard it called 'open-cell foam' and have been looking for it everywhere. Does it have another use where I could find it cheap? I asked at the big box stores and they dont even know what open-cell foam is.