Good place for large square sponges for a wet/dry?


Premium Member
Hello all,
I have a 72 bow front tank + 20 gallon sump with 180lbs LR and 120 LBS live sand. My wet/dry system in the sump is square, unfortunately I'm not home now to take the measurements, and has bio balls in it. In a few weeks I'd like to slowly remove the bio balls and place sponges in there instead. Anyone know of a good place online to find these sponges or what type to buy?
I don't use sponges anymore, just filter socks. The sponges like the bioballs can potentially be nitrate factories in your type of setup. If you have a submersible pump, you may want to use a prefilter sponge.
so....what should I put in the wet/dry? Nothing? If I did want to replace the bioballs with just large sponges, where could I buy some?