Has anybody ever used a "kaldnes bio filter"? I saw one for sale on Aquabid and wondered if they are legit or not. They don't look to be very difficult to make but before I spend the brain cells to try I thought I'd ask my livebearer cronies.
You can just google them, but the auction is in the mixed lots category under golden occies. I use both sponge and large box filters to keep the water clean.