JEROME Underwater for 5-10 Gallons Aquarium Filter Bio-stone Sponge Filter Media Color: Black, White; Material: Plastic,Sponge, Stone Net Weight: 52g; Usage Range: Fit for 5-10 Gallons Fish Tank Sponge filters provide both mechanical and biological filtration -- Simple, effective,easy to clean (squeeze in tank water), Working perfect getting your fish tank water super clean and clear. This sponge filter with stones inside, the air can easily dissolves in water, enhance the to release better. Easy to install, can be installed anywhere and can be easily hidden on the back wall of the aquarium; Perfect for shrimp tanks, crayfish, fry, fish or breeder aquariums. The sponge traps larger waste particles mechanically cleaning the water without trapping fish. They are useful for as breeding filter or as secondary filter, is the best choice for raising Shrimp and fishes. Filtration sponge provides vast surface area, cultivate high density nitrifying microorganism, playing the role of biological filtration. Tips: Soak the sponge in the aquarium water for 5 mins before use. Always use aquarium water to rinse and clean the sponge. Do not use hot water. Package includes: 1 X Fish tank Filter Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.