My hot tub water chemistry has always been good and never had any issues. My wife and I have not been using it much over the summer, but my daughter and her boyfriend have used it a few times. I told my daughter to put one scoop of shock in it after they get out. It seems that she was using the lid and not the scooper(probably 6-8 times too much). I checked the water the other day and the chlorine, pH and TH(calcium?) were extremely high. I didn't know at the time my daughter had been over dosing the shock. I left the lid off for a day with the pumps running and added some dry acid. The pH is now good and the chlorine finally came down to about 3ppm. TH is still high, about 450. The surface of the seats is really rough. Is this just the calcium? Or could that much chlorine have damaged the surface?
