Improve Water Quality The sponge filters pores have a large surface area where aerobic bacteria can propagate. Cultivating the nitrifying bacteria, will give you superior biological filtration in your tank. No Noise and Energy Saving The biochemical cotton filter is noiseless. Only requiring an air pump and airline tubing (sold separately) to work. These create numerous minute bubbles for increased oxygen flow. Safe Betta, fry and other small fish will NEVER get sucked up into the filter. The slow current from this filter is ideal when breeding and spawning discus, dwarf cichlids, guppies, and killifish. Fine Filtration As the water passes through the pores, the sponge will trap debris from your tank, leaving the water crystal clear. It is very efficient and will break down toxic waste from the tank. Easy to Wash and Reuse The sponge can be used multiple times. Instead of tap water, use water from the tank, to clean it, when doing water change. Simply rinse and squeeze a few times over until you see the water run clear from the sponge.