Confused by Pool store analysis

[poolmom06]

How much should I drain and refill??

[waterbear]

The reason the pH was reading so high is that chlorine levels above 10 ppm will cause bogus pH readings, whether strips or drops. They all use phenol red indicator! The only way to get an accurate reading when the chlorine is high is with a properly calibrated pH meter (and even that can suffer from some interferance!) The Taylor reagent is good up to about 15 ppm chlorine. LaMotte and most strips don't read pH accurately above 10 ppm and most cheapie kits don't work very well with chlorine above 5 ppm!