A Saltwater Chlorine Generator uses the salt in your pool water to create chlorine for your pool. The electrolytic cell generates chlorine gas and hydrogen gas. The chlorine gas rapidly dissolves into the water as Free Chlorine. The hydrogen gas bubbles out of the return (hydrogen is not soluble in water). How much Free Chlorine ppm is added depends on your pool volume, the rating of the generator, the runtime, and the % generation setting.