I'm still getting my water tested at a local pool store and using test strips. (I'm going to try and get better tests soon.) But, I can't keep chlorine in my pool because I can't keep the CYA levels up. They keep dropping about 8 to 10 points a week. I have no water loss. And I have 3 large tabs in which, allegedly should increase CYA. I had it to 39 ppm 5 days ago, and now its below 30 (according to test strips going to get a better reading today). Everyone keeps telling me I can't lose CYA without water loss, but I am.