I was in the same boat a few years ago. My CYA was off the chart due to years of use of 3" tablets. I drained 2/3 of my water and re-filled only to find I still had high CYA. Aylad is right, Switching to Salt won't help you. Complete draining is in all probability the simplest solution. I was also told that the CYA will also impermeate the liner as well, but I am not completely sure of this. Please tell us what your actual CYA reading is.