Nature2's patented technology uses minerals to kill bacteria and control algae for up to six months. This process of reducing bacteria and algae also decreases the amount of harsh chemicals used to keep your pool water balanced. In fact, using by Nature2 you can reduce the level of chlorine to just 0.5 ppm (1/2 part per million) Features: Mineral cartridge fits most cartridge filters Destroys bacteria and controls algae using natural minerals Reduces potential for stinging eyes, skin irritation, and unpleasant odors Will not harm pool equipment or stain pool Helps stabilize pH levels