You could have a rising PH due to plaster dust in the pool. Your numbers look fine - you could add a little more CYA to hit about 30ppm - but your chlorine should only need to be around 3-4ppm at a CYA of 30.

ALK at 80 is fine also - if you get this higher it will tend to raise your PH - so if it is stable at 80 - just leave it alone. My pool has ALK at 75-85 depending on whether PH is 7.2 or 7.5.

Just test the PH once a day and add SMALL amounts of acid to drop it a couple of points at a time. I add about 2 cups to the pool about every 3-4 days now - at first it was daily.