Just finished the medical treatment (steroids, and betacream) to eliminate the reaction caused by an allergy to non chlorine shock which includes as the main ingredient potassium monopersulfate. The rash is still not 100% gone, but about 98%, as there is still some slight redness in the most affected areas. When I nailed down the pur spa non chlorine shock as the culprit, I drained the tub, and refilled, adding only bromine tablets in a floater, and chlorine granuals (dichlor). 2 nights ago, while the reminant rash was still more visible and I had finished the steroids, I shocked the water with dichlor then I went back into the hot tub for a 45 minute test run...The bromine/chlorine levels were high from the chlorine shock, but with the shock chemical (oxidizer) absent, no rash, and no itchyness. Case solved.