Hydrogen peroxide is not a pool chlorine substitute.

No, not really, and don’t try it.

Hydrogen peroxide can technically oxidize organic stuff in water, but it’s not a practical chlorine replacement for a backyard pool. Chlorine does two things: sanitizes (kills bacteria, algae) and maintains a residual so the water stays clean. Hydrogen peroxide breaks down way too fast in sunlight—within hours—so you’d be pouring it in constantly. Plus, it doesn’t provide lasting protection. You’d end up with algae and bacteria before you know it.

People who use hydrogen peroxide are usually running advanced oxidation systems with UV or ozone, where it’s part of a bigger setup, not a standalone solution. For a typical residential pool, stick with chlorine or a bromine-based alternative. Hydrogen peroxide is great for cleaning cuts, not for keeping your pool from turning green.

Save the peroxide for the first aid kit.