A properly installed ozone generator is the most powerful single oxidizer you can use to keep the spa water clean and healthy. Ozone is up to 200 times more powerful than chlorine for oxidizing nasty things like bacteria and viruses, killing them on contact. Ozone can even help remove some of the metallic contaminants that can stain or corrode hot tub surfaces or damage metal components.
Not enough of us worry about the spa water balance and think that as long as the water is crystal clear, we are good to go. If the pH of the water in your hot tub isn't balanced properly, not only can it damage the tub and its components but it can also be harmful to your skin. Because the water in your hot tub is not drained after every use you obviously need to be more careful about this water than your regular baths.