I'm having problems with my CYA in my pool. I thought I had figured it out last year reading your posts. At the end of the season when I closed my pool I drained it way down. Over e course of the winter (we had which was a rainy season) I drained it 2 more times. When I opened it up the CYA was around 60 so I thought I was good. Having to shock it to clear it up the CYA was raised up to around 90 but the water was clear and all the chemistry was perfect. Instead of using tablets I decided to use shock to maintain. I was using around 2 pounds every 3 days and according to your chart I was maintaining around 8 to 10 on the FC. The CYA has been steadily raising up which I have around 150 CYA now. I am currently draining again to get it back in specks. I have been using SAM's shock is there anything better I can use that will not raise my CYA? I can't keep draining and filling that will be too much on my well.