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Just remember that just because something is "alternative" does not make it safer, or more enviromentally friendly than traditional sanitizer options like Chlorine or Bromine. Some have healthy sounding names like Mineral systems, but if you look into it these "minerals" are often Silver or Silver and Copper, ever hear of heavy metal poisioning? Remember sanitizers work by killing things in the water that you don't want to be there, one important aspect to this is water circulation regardless of the sanitizer used it is important for it to come in contact with whatever it is you want to kill. Personally I like the combination of ozone and chlorine, it is effective, and simple, but I don't know if there are special wood tub concerns. Any effective hot tub sanitation sytem is in reality a choice of pick your poision, because that is what it is.