Hydra Aquatics’ biological sponge filters provide mechanical filtration, and once the sponge has matured and grown bacterial colonies, it provides biological filtration as well. The sponge filters are easy to clean and have a weighted base for stability. It is excellent for safe and gentle filtration, such as in fry, quarantine, or breeding tanks where young fish could be sucked into the intake of standard filters. Best used with a 5 gallon aquarium.
