Fluval Carbona premium, research grade, low-ash carbonimproves water clarity and color, while also removing odors. Highly porous, it provides large amounts of surface area for adsorption of impurities. It effectively removes heavy metals, odors, discolorations, organic contaminants, and pollutants to leave your aquarium water crystal clear and sparkling. This product does not release phosphates. Carbon loses its activity without outward sign. Replace monthly to ensure that active adsorption is maintained. Carbon should always be removed when medication is being administered in aquarium water. Also, because carbon will adsorb a large percentage of the nutrients in plant fertilizer products, it should be used carefully when keeping live plants. For freshwater and marine environments. Premium select media for use in Fluval Canister Filters, ideal for all filters.