pH reducer: Use Muriatic Acid, if not at a grocery store, almost all hardware stores and home centers (like Home Depot) carry it.

To raise pH, use ordinary 20 Mule Team Borax. I find that 1 lb (1/4 box) will usually raise my 20,000 gallons .1 or .2 points, like from 7.2 to 7.3 or 7.4.

MWSmith2 will have to explain how to figure Borax exactly in his program.

Do remember, though, that Total Alkalinity's job is to buffer changes in pH, so a higher T/A may mean you need more Borax to raise the pH.