I have ozone and UV. Note that the UV is UV-C which is the disinfecting UV that you don't get from the sun, as it is absorbed by the atmosphere. The ozone only lasts a few seconds in the water, but it is a powerful oxidizer. I don't regard them as alternatives to chlorine, but they are a worthwhile supplement. UV-C for example kills cryptosporidium, while chlorine does not. Ozone helps eliminate chloramines. I still maintain normal chlorine levels in my pool, and after my initial warranty is up, I'll probably add a SWCG as an alternative to liquid chlorine. Ozone and UV-C are not alternatives to chlorine, even though the manufacturers claim up to 70% reduction in chlorine is possible. I don't believe that would be a prudent approach, personally. As to replacing UV bulbs, that depends on usage. My idiot pool builder wired the ozone appliance to run 24/7 regardless of whether the pump is running or not. When I asked why, when the bulb has a finite life, he said, "That's how I wired mine, and it works fine." He did subsequently put a timer in for the ozone and UV, which is a pain, since I have to manually reset the timer when I change pump run times, so I'll probably late get those connected to a flow switch. I regard ozone and UV-C as worthwhile supplements, especially for what they cost, to chlorine, and along with not allowing hillbillies in the pool, a part of having a clean and sanitary pool. I waited a really long time to get a pool. I'm 72, and I don't intend to contract a disease from my swimming pool. If it weren't too expensive and too hard to get a prescription, I'd even add tetracycline to the pool water!
