“Filteration is the heart of an aquarium. fish needs to be crystle clear water to stay in an aquarium healthy. Filteration can be biological, mechenical and chemical. Product Features: The Filter Sponge Absorbs Dirt and clears the water. Suitable for both fresh and salt water. Fully submersible and ideal for any aquarium filtration. Completely Submersible And, be fit for fresh water and sea water. Super Quite,efficient energy economizing,easy to clean.