I have one of Ben's kits but have been using up supplies in an hTh 6-way test kit from Wal-Mart that I bought while waiting for the good one to arrive.

I tested 7.5 pH, as usual, but thought it a bit strange that it wasn't trending upward. Granted, it usually does so slowly, but my last muriatic addition was 2 cups back on 8/21 - and this gunite pool is just 3 months old - and I have an SWCG.

So, because my hTh reagent was getting low anyway, I broke out the one in Ben's kit and - WOW - my pH was close to the 8.2 level color, probably 8.0

Being the skeptic that I am , I redid the test with a different R-0014 phenol red from a Leslie's/Taylor kit that I purchased to be able to test FC (again, prior to the arrival of Ben's). That test also confirmed the high 8.0-8.2 pH.

I know the hTh kit worked for higher pH early in the season, as my initial pH was 8.2. The kit has been stored out of the sunlight in the kitchen.

I don't know if anyone else has/had this problem, but if your pH seems to be staying put just a little too long and you have an hTh kit, better get another kit or have your water tested at a trusted pool store as a double check on your reading. Now, I'm out to the pool to add some muriatic acid!!