My pool water pH tests as 7.5 with the Taylor phenol red indicator kit or 7.6 with a similar BioGuard kit; however, the same water sample shows a pH of 7.0 when tested with a glass pH electrode and well calibrated pH meter from my research lab. Any idea why this discrepancy is occurring?
Other test results for the pool water are:
Free Cl 5.0 ppm
Combined Cl 0 ppm
Total alkalinity 110
Ca hardness 180
Borates 45 ppm
CYA 30 ppm
The pool is a 25K vinyl-lined pool in the southeastern US. Thanks for any insights!!