Chemi-pure Blue is the ultimate all in one marine aquarium filtration media, in an easy to use fine micron bag, that offers superior filtration and fantastic results in even the most advanced marine reef aquariums. Chemi-pure blue's unique formula is the finest marine aquarium filtration media available. Chemi-pure Blue lasts Longer and reduces the need for frequent water changes. For a Healthy, stable, crystal clear reef or marine aquarium use chemi-pure Blue!