Lactic Acid can be used in place of a sour mash. When using very pale malts it is easy to push your pH well above the 5.2-5.4 pH range. By using Lactic Acid you can easily lower the pH. Controlling the pH with Lactic Acid will allow you to obtain a greater mash efficiency. There is no set amount to use, but a pH meter should be used and the Lactic Acid added till you reach your desired pH.