Ozone is a powerful oxidizer of contaminants in water. It is easy to retro fit an ozone generator to a hot tub that is 'ozone ready'.
Ozonators help with spa water disinfection and reduce the amount of chemicals needed
It is important to realise that ozonators only kill contaminants in the ozone chamber and provide no residual protection to the main body of hot tub water so they can only be effective when water is circulating. No ozone unit will eliminate the need for chemical sanitizing products, however they do significantly reduce the level of chemicals needed.
To be effective, you should run your ozonator for at least 4-6 hours per day.