ESTIQ Mini Fish Tank Super Aquarium Air Driven Biochemical Sponge Fish Tank Corner Filter, Blue SPONGE FILTER provides both mechanical and biological filtration. Aerobic bacteria colonize the sponge, providing a bacterial substrate to facilitate the nitrogen cycle. In addition, the sponge traps larger waste particles, mechanically cleaning the water. CAN ABSORB dirt, quickly resolve fish feces and eliminate smell in water HELP IMPROVE water oxygen level, need to combine with an air pump ACHIEVE OXYGENATION and biofiltration double effect, keep water clean PACKAGE INCLUDE: 1 x Corner Filter (Air pump not included), Dimension: 7.5*7.5*7.5 cm. (L*W*H)