I jsut want to sing the praises of Bio-Chem Zorb. This stuff is just great. I got a mini-bag for my 12 gallon eclipse which was had a recurring tannin problem. The water was just nasty. A day after changing water it would look like i relieved myself in the tank. One night of the Zorb and everything was gone. Bow it is a few days of it being in there and my water is crystal clear and the fish are psyched. All this from a mini pouch which is only about 1/4 of my reservoir for filter media. In case anyone was wondering I covered it will filter pad to get out the larger junk. So if you are having a tannin problem, this is the stuff to get.*BOUNCINGS