Hydrogen peroxide (H₂O₂) is basically water with an extra oxygen atom. That extra oxygen is a party pooper for chlorine. When they meet, they react to form harmless salt, water, and oxygen gas. Basically, they cancel each other out like two grumpy cats.
This reaction is fast and safe for your pool, as long as you don’t go overboard. It won’t damage your liner or make your hair turn green. In fact, it’s a popular trick used by pool pros to drop chlorine levels quickly.
