I did a few quick searches to find out how long to aerate my pool to raise Ph and didn't really see a good answer.
So I'll give my example so maybe it will help others.
My Ph has stayed at 7.5 for weeks. I added 2 pucks the other day while taking a trip and my Ph dropped to 7.2. I like to keep it at 7.5 so I aimed my return jet straight up and left it like that from about 5pm till 7am the next morning.
Ph rose back to 7.5.
So to raise Ph in my size pool from 7.2 to 7.5 I had to aerate for about 14 hours. And I had the return jet pointed up as far as it would go.
Hope this helps somebody...