BIO-CHEM ZORB is the ultimate filtration medium for crystal clear water. BIO-CHEM ZORB contains a superior blend of resins and activated carbon which removes organic aquarium pollutants, including colors, odors, heavy metals and toxic gases as well as other compounds that carbon alone cannot remove. BIO-CHEM ZORB also removes light blocking impurities for improved growth of corals in saltwater and plants in freshwater aquariums.