Tideline Economy Pelletized Carbon is great for freshwater aquariums, ponds and saltwater fish-only aquariums. It is extremely affordable and the pelletized shape is easy to use. 55lb bulk size is great for store-use and service/maintenance clients. The large pore size is great for adsorbing organics and removing discoloration and odors. *please note, economy carbon is NOT virgin carbon. Please rinse thoroughly. Freshwater use only.