This filter media consists of high-grade activated carbon packaged in a ready-to-use pouch sized for FilStar XP canister filters. The carbon works to pull dissolved organic wastes, foul odors and water discoloration out of aquarium water as it passes through the filter. It is formulated for use in both freshwater and saltwater systems and is designed not to raise phosphate levels or alter pH. The pouch drops directly into the canister filter media basket, requiring no additional assembly. Because activated carbon becomes less effective as it saturates, the pouch is intended to be replaced on a regular basis to maintain water clarity. It is compatible with FilStar XP1, XP2, XP3 and XP4 canister filters.