Do you have a return eyeball that you can turn upward to create a lot of splashing on the surface?

In your pool, I would add about a cup or two of Borax at a time, wait 2 or 3 hours, retest and then redose til you get pH where you want it.

On the acid, I would probably do 1/2 to 1 pint doses. But, do NOT try to measure it. Just estimate it. Please read the "Using Muriatic Acid Safely" page in my signature above.