- Sponge filters are precisely what the name implies, a sponge through which the aquarium water is drawn. 

- This provides mechanical filtration, and once the sponge has matured and grown bacterial colonies, it provides biological filtration as well. 

- Sponges come in a variety of shapes and sizes, as well as pore sizes. This allows them to be adapted to a variety of filtration needs. 

-They can be powered by a number of methods, including air pumps, powerheads, or even another type of filter.