The Power Ionizer releases natural minerals to provide a cleaner pool and better quality of water. When the chamber light illuminates, it is time to replace the black mineral chamber. Each replacement chamber contains silver and copper minerals to naturally sanitize your pool. The chamber lasts approximately one pool season, and sometimes more, depending on pool size and usage. Please Note: This is a seasonal replacement part for use only with the electronic Power Ionizer by Main Access. Although chemical usage is drastically reduced with this product, a weekly “shock” program is recommended.