I have just recently been getting itchy after using my spa. The itch (no rash, mind you) occurs about 12 hours after getting out of the spa (and showering) and lasts 24+ hours, and is very intense. My husband, son and my friend that I soak most often with are not affected. It's mostly on the backs of my legs, and the insides of my elbows and knees. Not so much where my swimsuit covers. We are trying to figure out if it's a pH issue (but our test kit says about 7.6) or if I'm sensitive to the stuff in the MPS. We use chlorine and try to keep the levels between 2-5 ppm, have a Nature 2, and the spa has an ozonator (not sure if it's actually producing ozone). It's a 1996 Sundance Optima, and I had no issues the first 6 months that we had it (bought it refurbished in March 2010). I don't have the itch the first couple of uses after a water change, and the itch is worse if I stay in the tub longer. Help if you can please! I'm afraid to get back in the water!