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 such as a Stout or Porter, 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 (A.K.A. Gypsum) or Calcium Chloride is the most acceptable way to lower it.


How to Adjust The pH of a Mash

  • 1. To raise or lower the mash pH additions of calcium carbonate (to raise pH) or calcium sulfate / calcium chloride (to lower pH) are recommended.
  • 2. Add with ½ teaspoon at a time.
  • 3. Mix well.
  • 4. Recheck the pH after each addition.

If these are not available, or if you are brewing 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.


Another product available is called Mash Stabilizer. This product will automatically lower, or raise, your mash to 5.2 pH. All you do is add it to your mash tun, and it does the rest. Mash stabilizer is a very easy product to use that eliminates the need to use pH Strips or a pH meter.


Acid Rest Technique

There also is a technique called an ""acid rest"" which can be employed to lower the pH of the mash by varying degrees. The enzymes responsible for this are most active at a resting temperature of 95 °F for 15 minutes to a half an hour. So, start your mash at 95 °F for 15 – 30 minutes, then raise the temperature to the standard 152 °F for however long the recipe calls for.


If you are trying to raise the temp in our All Grain Brewing Cooler Systems, we recommend draining a gallon of wort from your mash tun, bring it up to a boil, and then add it back into your mash tun. Make sure to stir the hot wort back in so the higher temperature disperses throughout all the grains. This will usually get you very close to the 152 °F range.


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