1.Aquarium Foam Filter provide both mechanical and bio filtration. 2.The air infusion chamber produces minute bubbles which increase the oxygen solubility. 3.The Aquarium Foam Filter is easy to clean, simply take out the bio sponge, wash it in tank water every month then can reuse. 4.The box with ceramic balls, you can wash it and reuse it, and you can also change it to other filter media. 5. Don’t wash the Aquarium Foam Filter sponge in tap water or hot water, or it will reduce the QTY of beneficial bacteria. Only wash in tank water. 6.This Aquarium Foam Filter is safe for fish: soft sponge material, tinny holes, won't suck up your fish. 7.Excellent for small size fish like betta, dwarf cichlid, guppy, killifish, goldfish etc., or for hatcheries, maternity tanks, nano tanks and fry tanks, as the filter produces minimal water flow and has almost no way to suck the fish through the filter.