I have concerns over the TF100 test kit CYA test. Opening my pool for first time, 12k gallon. CYA was never added except for several chlorine tabs during opening, so I figure CYA was maybe 5 max. I measured and added 6lbs of dry CYA over the past 4 days, as I was worried about pH lowering. Testing CYA, i know its subjective, but if I didnt know I had added 6 lbs, I would say its 40, not 60. I attached pictures of 40,50,60. Black dot is still slightly visible at 50 to me. At 40 I cant see it at all. Anyone else have trouble with this? I followed instructions exactly.
As a side note, I was worried about pH, but its higher now?! one day after pool company opened pool, pH was 7.5(was winterized, they raised TA from 40 to 80, CH from 175 to 375, pH from >= 8.2 to 7.5,, and SLAM'd pool) Now 10 days later pH looks about 8.0, even after adding 6lbs dry CYA. I do have a spa spillover running 15 hours a day, just surprised.