It is a saltwater chlorine generator so generates chlorine, not salt. The chloride in salt is essentially boosted in energy (oxidation state) to form chlorine. When the chlorine gets used/consumed, it reverts back to being chloride salt. The main reason for having such a system is so you no longer need to manually dose with chlorine frequently. It also prevents the buildup of Cyanuric Acid (CYA) from use of chlorine tablets as that makes chlorine less effective over time often resulting in algae growth.