I had a problem with my ph level being too high. I added ph down every day and it didn't seem to make any difference.
I talked to my dealer and they recommended that I add the recommended dosage of ph down, wait 30 minutes, test it and if it was still high add the recommended dosage of ph down again. I repeated this every 30 minutes.
It took all day it seemed like but it finally came down and has remained at that same level since.