Spa ozone is the most powerful oxidizer and disinfectant that can be safely used in spa pools. Ozone kills all known bacteria, viruses, yeasts and a lot of other things that you don't want to know about. Ozone offers an alternative to heavy doses of traditional chemicals such as bromine and chlorine. Ozone controllers should be changed every 5 to 7 years. If you don’t have ozone you can easily retrofit it to your spa (controller link).