My CYA was getting a bit low (Seems that's the only chemical I add from year to year.) Everything else really stays in check.
So I was around 50PPM. Based on my pool size, I added 34oz by weight of CYA (I bought this CYA the first summer I had the pool, so it's now three years old - could it just be old and losing its strength?)
I add the CYA by slow pouring it down the skimmer. I've tried the socks, pantyhose, etc. Never seems to work well for me. So I always FIRST clean my cartridge filter, then pour it SLOWLY down the skimmer, then check it a week later (And do NOT clean the filter between.)
After a week, I went from 50-60ppm. Huh? It DEFINITELY lowered my pH as I was at 7.5 and by the end of the week I was down to 7.2.
At the time I added the CYA, these were my readings -