I'm in the middle of an ascorbic acid (AA) stain treatment. I dropped the CL to zero and the pH to 7.2 and then added the AA.
After adding the AA and letting it circulate overnight my LaMotte ColorQ and Taylor test kits still registered 7.2, but my LaMotte test strips and the local pool store read a pH of 6.8-7.0.
I spoke with LaMotte, and the tech I spoke with said that it was possible that the ascorbic acid might "complicate" the ColorQ and Taylor test kit readings.
I assume that the pH will drop, and the two sets of readings will converge, as I "burn off" the AA with chlorine.
My question is: Which testing tool and pH reading should I use as I try to hold the pH near 7.2 while bringing up the chlorine level?
(If pH readings during an AA treatment do depend on the testing tool being used, TFP might want to add this information to the stain treatment "cookbook.")