Bio-filtration supplement balls. Beneficial bacteria are needed to maintain a well-balanced aquarium. These bacteria live on the surfaces of the aquarium such as rocks, plants, decor and filter media. Unlike other liquid bacteria supplements, Aqueon PURE comes in an easy to dose ball providing a surface for nitrifying bacteria tto live before being added to the aquarium. Aqueon PURE also contains enzymes that help breakdown organic sludge that often cause poor water clarity. Using Aqueon PURE as part of a weekly routine will help reduce aquarium cleaning and maintenance. The bacteria and enzymes keep your aquarium balanced by breaking down the ammonia and nitrite that is created by fish waste and excess food.