I can't believe after having a pool for 25+ yrs. how much the pool store has bamboozled me!!!!!!!! After having a problem this year with no free chlorine in my SWG IG pool I stumbled across this forum and now there is no looking back. I can't believe the discrepancy in the pool stores numbers and my numbers with my brand new TF100 test kit. Talked to a wonderful man on the phone the other day when I thought my calcium hardness chemical wasn't working or was old and he gave me all the info I needed to make a correct test. The pool company said my CH was 254 and when I tested it was 500. So right off the bat this website has helped me and the test kit has proved invaluable. Wish I had come across it before I dumped all that shock in there with all that calcium in it (had to be over 25 bags) They didn't know I needed to shock up to a high level because my stabilizer is at 100. Anyway, I finally dumped in 9 bags and that did it. Now I will only use liquid chlorine if I have to shock. Hopefully the CH and stabilizer will come down some over the summer because taking out a bunch of water now is not feasible. I retested yesterday and now I'm getting 375 for CH so I guess thats a lot better. Anyway, just wanted to say thanks and I will become a supporter and I won't need to go anywhere else for my pool questions. Thanks again.