All my pool numbers test right on with my TF-100. My CYA is at 40 but has been growing week to week. I started the season low at 12 and have been able to treat it to get to 20. I have been using the 3 in triclor pucks for chlorination .. so I know it is adding some CYA. Over about 2 or 3 weeks it has rissen to 40. At what point should I be concerned?