I have the same question about my ozonator. I have the Barefoot spas 57LP. It’s a small one. I think it used to be called the PR5. Anyway, i just got it last month and trying to learn more about this ozonator. Some places I read says it has an indicator light to tell when its on, and mine does so I guess I good with a green light. Green means go and good right? It keeps the water pretty clean without a lot of chemicals. We don’t really put much chlorine in there. Plus, I read when you put a lot of chlorine in the water, this kind of ozonator with the UV light and ozone gas actually purifies the chlorine out of the water. Pretty interesting the way it works.