Bio balls provide a place for all the good nitrifying bacteria you need in your tank to live. The surface of each bio ball is designed to have as much surface area as possible so the bacteria have as much as possible to cling to. They will also keep the PH balance at neutral for a long time and can absorb and dissolve poisonous ions. Overall a very efficient way of improving water quality!

Bio Balls work effectively in pond or aquarium filters. Click the link to view.