Kent Marine Reef Carbon contains essential Activated Carbon for use in marine and freshwater aquariums. Contains a fine pelletized bituminous coal based carbon with pore sizes that range from 20 to 2,000 Angstrom. Ideally suited to remove organic pollutants, stain, and entrained toxic gases. Kent Marine Reef Carbon is super activated with very high iodine and molasses numbers with less than 0.2% ash. Will not leach phosphates or promote undesirable algae growth and is well suited for sensitive fish and reef systems. Kent Marine Reef Carbon is very active and only requires 1/4 lb per 100 gallons of aquarium water. Place in fine mesh bag or filter chamber directly in water flow. Shipping weight: 1 1/4 lbs.