Literally have no pet store bear by and I'm trying to fill a gap in my overflow so an eel I have won't get into the sump. Can't find sponge filter material ANYWHERE in my local area and the closest shop to me is 2 hours away. Got a car sponge from Walmart. Rinsed the crap out of it in RODI water that was treated with prime. Cut it to size; approx a 5x5" piece. Placed in my overflow box and walked away taking it was good. Best thing I know, I have microbubbles all in my DT! I open my sump and my skimmer was overflowing! Emptied it out and placed the cup back on and plugged it in. Instantly overflowed again. The sponge was just a standard cheap $1.50 sponge. No chemicals in it or soaps preloaded. What gives?
