Boyu Biological Sponge Filter This simple internal filter operates with the power of any air pump connected to it via a flexible hose. It can also be used as a pre-filter for external filters or power heads. Sponge filters provide suitable mechanical and biological filtration, depending on the filter size and bio-load in the aquarium. They are economical as they consume only a small amount of energy to pump the required air. Diameter: 7.5 cm Height: 9.3 cm Height including exhaust tube: 19 cm (the exhaust tube can be shortened by cutting)