This cartridge contains natural purifying minerals that are known to help control bacteria and prevent algae. You can experience softer, cleaner spa water naturally with this product. The Spa Mineral Purifier can be used with all sanitizing systems including bromine, chlorine, ozone and non-chlorine shock. Place the purifier cartridge into your spa filter. When used with a minimal sanitizer residual of 0.5 ppm, the Spa Mineral Purifier can give you clear water for up to 4 months!