The Red Sea REEF-SPEC Carbon filter media will provide your aquarium with the best water quality which is suitable for freshwater, marine, and reef aquariums. This media is cost-efficient as it lasts longer than other carbons of lower quality. REEF-SPEC assures that specific organic pollutant will be extracted in reef aquariums, with enormously low phosphate leakage and minimal ash content. This also assures that the pH in your aquarium water will not be affected. This Carbon filter media has a high total absorption capacity and includes one filter bag.