The Bio Balls can filter impurities to reduce growth, keep your fish tank clear and . The internal biochemical cotton improves the filtration effect, stabilizes the quality and accelerates the maturation of nitrifying . Besides, they can be used in various filters, like upper filter, filter bucket, fish tank bottom filter, hanging wall filter, etc. Features -Color:Black -Material:PVC -Size:2.60X2.60X2.60cm/1.02X1.02X1.02in -They are used to swimming pools and filter impurities, which can save you time. -In the filtration process, the efficiency is high, the filtration is fast, and the sewage interception capacity is large. -These Bio Balls are reliable, and they are suitable for filtration of various qualities. -They have the advantages of being lightweight, having high strength, and having good elastic effects. -High density, sturdy or non-deformed after soaking. filter the fine substances in the . Package list: Aquatic Bio Balls