Our bio balls can be used not only in biochemical filtration systems in seawater, but also in biochemical filtration systems in freshwater Perfect for using as fish tank filter, aquarium filter media, pond filter media. Great help to restore the natural water quality, and provide the most suitable living environment for your fishes. When the water flows through internal space, prolonged the time, using the nitrifying bacteria to achieve the effect of biochemical filtration. Strengthened the effect of filtering bacteria, lightweight and easy to carry.