Ozone and UV do different jobs. Both help.

They tackle different problems.

UV light zaps microorganisms in the water as it passes through the chamber. Kills bacteria, viruses, and protozoa instantly. Works great for sanitation, but only on the water that flows past the lamp. Once the water leaves the chamber, there’s no residual protection.

Ozone gas blasts through the water and oxidizes organic contaminants — sweat, oils, lotions. It also breaks down some chlorine byproducts, which reduces that “pool smell.” Ozone dissipates quickly (within minutes), so it also leaves no residual. It’s more about water clarity and reducing chemical load than outright kill-everything reliability.

You can use either standalone, but most serious pool setups combine both. If you have to pick one, UV is the safer bet for actual sanitation. Ozone helps water feel nicer and cuts down on chlorine use, but it’s less consistent.

Either way, you still need some kind of residual sanitizer (chlorine, bromine) to keep the pool safe between treatments.