Ozone generators use a special ultra-violet light to kill bacteria. Like the cartridge systems
mentioned above, ozone generators only kill contaminants in the ozone chamber and provide no
residual protection to the water in the pool. To be effective, the pool pump must run almost all of
the time. Ozone and UV units designed for swimming pools are very expensive and draw a lot of electric current. These units are better suited for spas but are not practical for the volume of water in most swimming pools.
Even the best ozone/UV units will not totally eliminate the need for chlorine or other chemical oxidizing agents in the pool water; most of the manufacturers quickly acknowledge this. Keep in mind an outdoor swimming pool receives surplus UV daily, and neither ozone or UV provide ANY swimmer-to-swimmer bacteria or viral protection.