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Since this can be used with sanitizers, I was thinking it might be just the thing for treating a hot tub prior to taking a vacation where it won't be used a week or two.
The concept works. It's used in municipal water treatment, farm animal water treatment, food processing water treatment and other uses where chlorine or other chemicals are not desired. Not saying it works in spas, but the concept has been tested and does work elsewhere.
honest question...exactly what concept are you referring too?