A variety of supplemental disinfection process equipment is being marketed for use on swimming pools. The most common are copper/silver ion generators, ozone generators, and ultraviolet light generators. While each process provides some disinfection activity, they are not accepted as primary disinfectants in public swimming pools because they are either too slow or do not provide a disinfectant residual. Supplemental disinfection equipment, if used, must be used in conjunction with a free chlorine or bromine residual.