Larry,

Every pound (which is about a cup) of 20 Mule Team Borax requires about 7.7 ounces of Muriatic Acid (31.45% HCl) to keep the pH the same so you can add one and then the other in smaller quantities to keep the pH more stable (you don't mix them together, of course, you just put them into the pool one after the other).

For your size pool it would take 1219 ounces or about 76.2 pounds of 20 Mule Team Borax which is about 16 boxes. It would take about 582 ounces of Muriatic acid to keep the pH the same after adding the Borax. Of course, you should add about half of each of these amount (alternating in smaller additions of each) and then measure your Borates level on the test strip just to be sure you don't go to far and that my calculations were correct.

Richard