How can the pH of the mash be adjusted?
If the pH of the mash is too low (too acidic) the addition of calcium carbonate will work well to raise it. In some cases, especially if you are making a very dark beer, you may have to settle for a mash pH as low as 5.0 but under no circumstance should you add more than 2 teaspoons of calcium carbonate to a five-gallon mash. If the pH of the mash is too high (too basic/alkaline) the addition of calcium in the form of calcium sulfate (gypsum) or calcium chloride is the most acceptable way to lower it. In either event starting with ½ teaspoon additions at a time is recommended. Mix well and recheck the pH after each addition. If this is not available or if you would like to brew with very soft water, then the addition of phosphoric acid can accomplish acidification of the mash. Teaspoon additions can be added incrementally until the desired pH is achieved. There is, also, a technique called an “acid rest” which can be employed to lower the pH of the mash by varying degrees. The enzymes
