Quote Originally Posted by waterbear
A full box of borax is 4 lbs 12 oz.....almost 5 lbs. That could explain the pH rise. 3/4 to 1 cup of acid should get you back into the ballpark by my calculations.
Evan,

From our previous discussions and your own experience, 1 box of Borax (4 pounds, 12 ounces) requires 4 cups, 7 ounces of Muriatic Acid to balance the pH. If his son did put in 4 cups of Muriatic Acid, then I would expect about 4 pounds of Borax would be required to neutralize it. About a pound of Borax is equivalent to a cup of Muriatic Acid.

Of course, he saw a much larger rise so something is amiss. Either his son did not in fact put in 4 full cups of acid, or more than 4 pounds of Borax was used, or our calculations our wrong.

Richard