This Nature 2 replacement cartridge releases the same minerals found in nature to control bacteria, algae and viruses. Significantly reduces the amount of chlorine and chemicals needed to maintain your pool water. For in ground pools up to 45,000 gallons. Cartridge will last for approximately six months. Features: Replacement mineral cartridge for all G45 vessels Destroys bacteria and controls algae using natural minerals Reduces potential for stinging eyes, skin irritation, and unpleasant odors; helps stabilize pH levels Will not harm pool equipment or stain pool