Provide both mechanical and biological filtration.
Simply install an airline into the unit and provide both aeration and filtration for your fish. Aerobic bacteria colonize the sponge providing a bacterial substance to facilitate the nitrogen cycle.
The sponge traps larger waste particles mechanically cleaning the water without trapping baby fish.
Product dimensions 3.8 L x 1.8 W x 5.5 H sponge dimensions 1.8 D x 3.0 H. They are useful for as breeding filter or as secondary filter. Or they can be used as pre filtration unit by fitting to an external or a top filter.