Can I use hydrogen peroxide as a substitute for chlorine in my pool?

No, not really, and don’t try it. Hydrogen peroxide breaks down too fast in sunlight—within hours—so you’d be pouring it in constantly, and it doesn’t provide lasting protection against algae and bacteria. It’s only used in advanced oxidation systems with UV or ozone, not as a standalone solution for a typical residential pool. Stick with chlorine or bromine.