When I bought my Barefoot Spa 2 years ago, only some of the spas had ozone installed. It was an option for us as an upgrade when we bought it. I’m glad we did it because it works wonders. Th eonly thing I’ve had to replace is the little bit of shock from the kit they gave me. Again, we’ve had the thing for 2 years! I am worried thought that the ozone system is running out.. not sure.