The Solar Pool Ionizer kills algae and prevents it from returning. The unit simply floats in your pool and uses copper ionization to kill algae before it has a chance to form and take over your pool. WORKS WITH ALL POOL TYPES: In-ground, aboveground, saltwater, and chlorine pools. Also safe for all finishes, including, plaster, pebble, quartz, tile, and vinyl liners. EVERYTHING YOU NEED TO STOP ALGAE GROWTH: This includes one copper anode, metal cleaning brush, and a copper test kit. Copper anode lasts approximately one year before needing replacement.