Internal air bio sponge filter for simple aquarium cleaning. The BOB internal sponge filter is equipped with a pump that draws in water. Its capacity is therefore greater than that of an air filter. It has the great advantage of filtering more water and increasing the flow rate in the aquarium. Thanks to its fine sponge, this 2-sponge filter is absolutely risk-free, even for shrimps. It even removes small particles from the water. Additional and replacement sponges for the BOB sponge filter are easy to order and available from stock.