Until now I've been using test results and advice from Pool Store. Always thought they were pretty honest but they had recommended level of cya as 30-150 and never recommended I switch away from pucks even though my level was 100+. I came across this site and bought a TF100 kit. Is the reason some pool stores recommended cya levels are so much higher because they want you to buy more chlorine? I drained 1/3 of the pool and got it down to 85-90 cya. What do I need to do next?