Renew, 4 L / 1 gal. Phosphate free carbon substitute for organic removal in the aquarium Ideal for use in systems where phosphate released from all activated carbon poses a problem Less aggressive than carbon making it well suited for reef and planted aquaria Removes organics and particulates in the sub micron range; It will also help control ammonia nitrates and phosphates Beneficial in soft water aquaria where the pH raising property of many carbons is not an asset