Have used the hot tub - 250 gal Nordic - since March 2017. No problems for 3 months. Started - in July getting a bit of a rash on my back and lower sides. Every hair follicle got inflamed and had a white puss ring. Right after I got sucked into using AHH-Some. Don't know if that exacerbated the rash or not. It'd last a couple of days then diminish. Started lasting longer and more severe. Went to the dealer and discussed a solution. Both of us thought it might be caused by chlorine. We tried Nature2 + Shock. WOW! The rash really got bad. Started online research and many articles suggested a lot of people are allergic to Shock. Drained and cleaned the hot tub. Added chlorine granules only. 2 days - no rash. Added PH and Alk.- no rash. Used the tub today for 45 minutes-no rash. JFYI in case anyone might get similar symptoms.