When I do the CYA test that is included in the TF-1000 kit, it fluctuates between 60 and 80. Over the course of the last 6 weeks, it has gone from 60, up to 70, then 80, then back to 70 and today it was 80 again. Is this because I'm not doing the test correctly (or judging the results correctly)? Or can CYA really go up like that? I chlorinate using 10% liquid chlorine and I have not used tabs or anything else with conditioner (I've only ever put liquid chlorine, Muriatic Acid and baking soda). In those 6 weeks, the pool level has gone up about 4 inches, then down about 2 inches due to rain/evaporation.
What else can affect CYA?