Hot Tub Mineral Purifiers use elemental Silver and Copper to kill bacteria in spa water. These products are used in conjunction with small amounts of Chlorine and Non Chlorine shock to keep your water clear and free from bacteria. Replace these purifiers every 4 months and use them in conjunction with proper water balancing for the most poplular chlorine free way of water treatment we offer. PoolGeek.com offers multiple brands of No Chlorine Mineral Purifiers.