I've got a 15 month old plaster SWG pool that continues to have PH drift. About every 4-5 days I add acid to bring it down. I usually bring it down to the 7.2 range so I don't have to add every other day. Although the PH drift was much worse a year ago I''m still frustrated. I believe that the water is suposed to stablize around 7.6 - 7.8 for a SWG. Is that correct? The rise is slower once its gets higher. Should I let it go to see where it stablizes? My tester only goes to 8.0 so it's hard to read the higher PH levels.
SWGs tend to cause upward ph drift. I do not think the drift typically stops at any particular level. So your experience is pretty normal. What is your TA? If it is much above 80 ppm, this will usually cause excessive drift for SWG pools.
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What is your TA level? To minimize PH drift, TA should be around 60 or 70.
What is your TA level? To minimize PH drift, TA should be around 60 or 70.
TA is about 50. In the winter I could go about 1 1/2 weeks before needing acid. I guess the temp, outgassing by the SWG, sheer decents and my children are responsible for the PH rise. 
I wouldn't let the TA get any lower than 50. Doing so can cause funny things to happen to pH levels with fairly simple changes in the pool environment.
Since your plaster has cured, the pH rise won't be as pronounced as it was during the first year of your pool's life while the plaster was curing. Still though, running a SWCG virtually guarantees that you will need to address pH rise with acid on a regular basis. It's just part of the deal.
Since your plaster has cured, the pH rise won't be as pronounced as it was during the first year of your pool's life while the plaster was curing. Still though, running a SWCG virtually guarantees that you will need to address pH rise with acid on a regular basis. It's just part of the deal.
Probably not the answer any of us want but a candid and accurate answer nevertheless. It simply comes with the territory.
minimize aeration - my SW pool used to drift up VERY fast. Got rid of my pooldevil skimmers, and 2/3 of the problem went away. I still have to adjust it down with MA once a week or so, but we use it a LOT.