The Mineral Purifier Cartridge creates a very comfortable, safe spa environment for your well being and comfort. It makes your spa virtually chlorine and bromine free. The Mineral Purifier eliminates the need to use chlorine or bromine on a daily basis or with a floating feeder. You just use a small dosage of chlorine once a week and it will naturally disappate within about 24 hours. This means you are relaxing in chlorine/bromine free water that is clean, clear and safe. The Mineral Purifier will last 3 months. You can also sign up to pre-pay for a year, get a discount, and get the Mineral Purifier shipped to you automtically each month.