Ozone Sterilization turns on automatically as soon as the hydro pump is turned on along with the in – line water heater. Ozone is a naturally occurring oxidative. Using a process called “cellular lyses,” the ozone eliminates mold and bacteria from the bathwater and prevents mildew and odor from accumulating. This is especially useful when the tub is regularly used by more than one person. Not only does the ozone protect the tub’s surface from contaminates, but it also gets into the jetting lines and prevents harmful agents from forming there.