Bio Balls,Govine 500g Bio Balls Aquarium Pond Fish Tank Filter Ceramic Rings Filtration Media Bio ceramic rings are used to keep your bacteria colony to convert ammonia from waste to nitrites and nitrites to nitrates. Bio balls work as a biological filter media and give a home for beneficial bacteria where they can settle and be fed by water and oxygen. They promote gas exchange and increase dissolved oxygen levels. Great for any freshwater or saltwater fish tank or mini-reef aquarium. Fish Tank Filter are simply rinse and use. There is a hollow in the middle of the biological column filtering medium, can provide an anaerobic environment, reducing the content of nitrates in water, and promote more healthy water quality. Package Include 1 bag of 500g Bio Balls