when I use an air stone in my water tank I also notice my PH goes up.
If I don't aerate, I only need 3-4 drops to bring it down to 6.5, if I aerate I need 8-9 drops per 4L of 85% phosphoric acid.
I did a little test of it on my one grow, the link below is to the image of the results. its by no means perfect, and only used just over 1L of tap.
growdiaries.com/diaries/129773-grow-journal-by-m0use/week/704902
I would bubble the water for 40min with PH adjustment before adding into the tank to help avoid any unnecessary ph fluctuations
But I don't know if that works for you. Can try it out and see how well it works for yea.
Good Luck!