Although spa ozonators are not stand-alone systems, they do assist in cleansing spa water and therefore are a great addition to any hot tub. Spa ozonators are used in combination with small amounts of chlorine or bromine to cleanse the water in your tub. Corona discharge (CD) ozonators and UV ozone generators are two popular spa ozonators. CD ozonators use electrical currents to convert air to ozone; whereas UV ozonators use ultraviolet lighting to do the same thing. Hot tubs today are often equipped with ozone generators, eliminating the hassles of having to install one yourself. If you own an indoor spa, ensure that the ozone generator is equipped for indoor spas, as some are not.