Water Chemistry Part 2 of 2: CaCO3 & pH

In Part 1 of this topic I mentioned how minerals like Calcium and Magnesium contribute to healthy fermentation, clarity and flavor stability.  Here, in Part II, we’ll identify the ideal concentrations of each, address brewing salt additions and explore the effects of pH and alkalinity on your mash conversion.  Finally, I’ll explain how to use different ratios of chloride to sulfate to accentuate certain ingredients in your recipe.  

Remember, hardness (expressed on your water report as “Total Hardness as CaCO3”) is not a bad word in brewing.  Calcium and magnesium are the two main ions that contribute to hardness.  Both are necessary for yeast health.  Calcium is also responsible for helping to promote enzymatic activity in your mash as well as other biochemical reactions.  The optimal brewing water range for Calcium is 50-150 ppm and for Magnesium, 10-30 ppm.  Magnesium additions are seldom needed as malt usually contributes enough magnesium to reach these ideal concentrations.  

There are several great (and free!) brewing water calculators available online.  Start by inputting your own water’s data and then adjust to these ideal ranges as needed.  If your calcium concentrations are lower than the ideal range, just a few grams of Gypsum (Calcium Sulfate) or Calcium Chloride can make a big difference.  Be aware of the other ion in each compound (sulfate and chloride) as these concentrations will also be affected.  If your concentrations are higher, you might consider cutting your water source with distilled, deionized or reverse osmosis water.  A 1:1 dilution will cut your concentrations in half.  In most cases, this should get you within an acceptable range for brewing.  

Alkalinity and pH are often confusing terms for all grain brewers.  Alkalinity (expressed as either “Total Alkalinity as CaCO3,” “Bicarbonate” or “HCO3”) represents the concentration of anions like bicarbonate in your water and can be problematic at levels over 250 ppm.  Alkalinity acts as a pH buffer.  The higher the concentration the more resistant to change your mash pH will be.  Ideal mash pH should be between 5.1-5.5.  If higher, mash enzymes are still very active but tannin extraction from husk material is more likely especially around a pH of 6.  A pH lower than 5.1 will hinder enzymatic activity, therefore, reducing efficiency and could potentially affect flavor.   

Brewers are more likely to find themselves battling high mash pH as a result of high alkalinity more than other factors.  The specialty malts in your recipe will help lower your mash pH but not drastically.  As the degree of roasting in specialty malt increases so does the acidity.  This acidity can help to counteract higher mash pH but if you’re still not in that 5.1-5.5 range you may need additional acid.  You can find acid in multiple forms including acid malt, lactic and phosphoric acid.  I like to keep a couple pounds of acid malt on hand for small adjustments.  How much should you use?  1% of your total grist by weight should lower your mash pH by one-tenth of a point.   Concentrations and results will vary depending on the acid you use and may take some trial and error to perfect.        

Brewing water pH can vary greatly depending on the source.  An ideal range is 6.5-8.5 but the pH of your water is far less important than the pH of your mash.  I recommend mashing in first.  Allow the mash to settle for 5 minutes.  Then take a pH reading and adjust appropriately.  

Chloride and sulfate ions can be used to steer the flavor profile of your beer in your intended direction.  Sulfate helps to accentuate hop bitterness.  Chloride will do the same for malt character.  A well-balanced beer’s chloride to sulfate ratio might be 1:1 but it still depends on your recipe.  To highlight bitterness, try increasing your ratio to 1:2 or 1:3.  Research has shown that some styles can be brewed with a ratio as high as 1:8 without encouraging harsh bitterness.  The ratio applies to chloride in a similar manner.  A chloride to sulfate ratio of 2:1 or 3:1 can help to accentuate a more malt-centric recipe.     

So, keep your calcium levels between 50-150 ppm, your alkalinity between 0-250 ppm, your mash pH between 5.1-5.5 and adjust your ratio of chloride to sulfate to the characteristics of the style you intend to brew.  After that, bring us a sample.  You know, for “sensory evaluation.”

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