Equipment Glossary Acknowledgements


Site Map
Introduction
Section 1
Brewing Your First Beer With Malt Extract
Section 2
Brewing Your First Extract and Specialty Grain Beer
Section 3
Brewing Your First All-Grain Beer
14 How the Mash Works
15 Understanding the Mash pH
16 The Methods of Mashing
17 Getting the Wort Out (Lautering)
18 Your First All-Grain Batch
Section 4
Formulating Recipes and Solutions

 

 

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Chapter 15 - Understanding the Mash pH

15.1 Reading a Water Report

To understand your water, you need to get a copy of your area's annual water analysis. Call the Public Works department at City Hall and ask for a copy, they will usually send you one free-of-charge. An example for Los Angeles is shown in Table 12. Water quality reports are primarily oriented to the safe drinking water laws regarding contaminants like pesticides, bacteria and toxic metals. As brewers, we are interested in the Secondary or Aesthetic Standards that have to do with taste and pH.

There are several important ions to consider when evaluating brewing water. The principal ions are Calcium (Ca+2), Magnesium (Mg+2), Bicarbonate (HCO3-1) and Sulfate (SO4-2). Sodium (Na+1), Chloride (Cl-1) and Sulfate (SO4-2) can influence the taste of the water and beer, but do not affect the mash pH like the others. Ion concentrations in water are usually discussed as parts per million (ppm), which is equivalent to a milligram of a substance per liter of water (mg/l). Descriptions of these ions follow the water report.

Table 12 - Los Angeles Metropolitan Water District Quality Report (1996 data)

Parameter

State Maximum
Contaminant Level
(mg/L)

Delivered Average
(mg/L)

Primary Standards

  

Clarity

.5

.08

Microbiological

  

Total Coliform

5%

.12%

Fecal Coliform

(detection)

0

Organic Chemicals

  

Pesticides/PCBs

  

(various - JP)

(various - JP)

ND

Semi-Volatile Organic Compounds

  

(various - JP)

(various - JP)

ND

Volatile Organic Compounds

  

(various - JP)

(various - JP)

ND

Inorganic Chemicals (list edited - JP)

  

Arsenic

.05

.002

Cadmium

.005

ND

Copper

(zero goal)

ND

Fluoride

1.4-2.4

.22

Lead

(zero goal)

ND

Mercury

.002

ND

Nitrate

10

.21

Nitrite

1

ND

Radionuclides

  

(various)

(various - JP)

(various - JP)

Secondary Standards - Aesthetic

  

Chloride

*250

91

Color

15

3

Foaming Agents

.5

ND

Iron

.3

ND

Manganese

.05

ND

Odor Threshold

3

-2

pH

No Standard

8.04

Silver

.1

ND

Conductance (mmho/cm)

*900

984

Sulfate

*250

244

Total Dissolved Solids

*500

611

Zinc

5

ND

Additional Parameters

  

Alkalinity as CaCO3

NS

114

Calcium

NS

68

Hardness as CaCO3

NS

283

Magnesium

NS

27.5

Potassium

NS

4.5

Sodium

NS

96

* = Recommended Level
NS = No Standard
ND = Not Detected

Calcium (Ca+2)
Atomic Weight = 40.0
Equivalent Weight = 20.0
Brewing Range = 50-150 ppm.
Calcium is the principal ion that determines water hardness and has a +2 charge. As it is in our own bodies, calcium is instrumental to many yeast, enzyme, and protein reactions, both in the mash and in the boil. It promotes clarity, flavor, and stability in the finished beer. Calcium additions may be necessary to assure sufficient enzyme activity for some mashes in water that is low in calcium. Calcium that is matched by bicarbonates in water is referred to as "temporary hardness". Temporary hardness can be removed by boiling (see Bicarbonate). Calcium that is left behind after the temporary hardness has been removed is called "permanent hardness".

Magnesium (Mg+2)
Atomic Weight = 24.3
Equivalent Weight = 12.1
Brewing Range = 10-30 ppm.
This ion behaves very similarly to Calcium in water, but is less efficacious. It also contributes to water hardness. Magnesium is an important yeast nutrient in small amounts (10 -20 ppm), but amounts greater than 50 ppm tend to give a sour-bitter taste to the beer. Levels higher than 125 ppm have a laxative and diuretic affect.

Bicarbonate (HCO3-1)
Molecular Weight = 61.0
Equivalent Weight = 61.0
Brewing Range = 0-50 ppm for pale, base-malt only beers.
50-150 ppm for amber colored, toasted malt beers, 150-250 ppm for dark, roasted malt beers.
The carbonate family of ions are the big players in determining brewing water chemistry. Carbonate (CO3-2), is an alkaline ion, raising the pH, and neutralizing dark malt acidity. Its cousin, bicarbonate (HCO3-1), has half the buffering capability but actually dominates the chemistry of most brewing water supplies because it is the principal form for carbonates in water with a pH less than 8.4. Carbonate itself typically exists as less than 1% of the total carbonate/bicarbonate/carbonic acid species until the pH exceeds 8.4. There are two methods the homebrewer can use to bring the bicarbonate level down to the nominal 50 - 150 ppm range for most pale ales, or even lower for light lagers such as Pilsener. These methods are boiling, and dilution.

Carbonate can be precipitated (ppt) out as Calcium Carbonate (CaCO3) by aeration and boiling according to the following reaction:

2HCO3-1 + Ca+2 + O2 gas --> CaCO3 (ppt) + H2O + CO2 gas

where oxygen from aeration acts as a catalyst and the heat of boiling prevents the carbon dioxide from dissolving back into the water to create carbonic acid.

Dilution is the easiest method of producing low carbonate water. Use distilled water from the grocery store (often referred to as Purified Water for use in steam irons) in a 1:1 ratio, and you will effectively cut your bicarbonate levels in half, although there will be a minor difference due to buffering reactions. Bottom Line: if you want to make soft water from hard water (e.g. to brew a Pilsener), dilution with distilled water is the best route.

Sulfate (SO4-2)
Molecular Weight = 96.0
Equivalent Weight = 48.0
Brewing Range = 50-150 ppm for normally bitter beers, 150-350 ppm for very bitter beers
The sulfate ion also combines with Ca and Mg to contribute to permanent hardness. It accentuates hop bitterness, making the bitterness seem drier, more crisp. At concentrations over 400 ppm however, the resulting bitterness can become astringent and unpleasant, and at concentrations over 750 ppm, it can cause diarrhea. Sulfate is only weakly alkaline and does not contribute to the overall alkalinity of water.

Sodium (Na+1)
Atomic Weight = 22.9
Equivalent Weight = 22.9
Brewing Range = 0-150 ppm.
Sodium can occur in very high levels, particularly if you use a salt-based (i.e. ion exchange) water softener at home. In general, you should never use softened water for mashing. You probably needed the calcium it replaced and you definitely don't need the high sodium levels. At levels of 70 - 150 ppm it rounds out the beer flavors, accentuating the sweetness of the malt. But above 200 ppm the beer will start to taste salty. The combination of sodium with a high concentration of sulfate ions will generate a very harsh bitterness. Therefore keep at least one or the other as low as possible, preferably the sodium.

Chloride (Cl-1)
Atomic Weight = 35.4
Equivalent Weight = 35.4
Brewing Range = 0-250 ppm.
The chloride ion also accentuates the flavor and fullness of beer. Concentrations above 300 ppm (from heavily chlorinated water or residual bleach sanitizer) can lead to mediciney flavors due to chlorophenol compounds.

Water Hardness, Alkalinity, and milliEquivalents
Hardness and Alkalinity of water are often expressed "as CaCO3". Hardness-as referring to the cation concentration, and alkalinity-as referring to the anions i.e. bicarbonate. If your local water analysis does not list the bicarbonate ion concentration (ppm), nor "Alkalinity as CaCO3", to give you an idea of the water's buffering power to the mash pH, then you will need to call the water department and ask to speak to one of the engineers. They will have that information.

Calcium, and to a lesser extent magnesium, combine with bicarbonate to form chalk which is only slightly soluble in neutral pH (7.0) water. The total concentration of these two ions in water is termed "hardness" and is most noticeable as carbonate scale on plumbing. Water Hardness is often listed on municipal water data sheets as "Hardness as CaCO3" and is equal to the sum of the Ca and Mg concentrations in milliequivalents per liter (mEq/l) multiplied by 50 (the Equivalent Weight of CaCO3). An Equivalent is a mole of an ion with a charge, + or -, of 1. The Equivalent Weight of Ca+2 is half of its atomic weight of 40, i.e. 20. Therefore if you divide the concentration in ppm or mg/l of Ca+2 by 20, you have the number of milliequivalents per liter of Ca+2. Adding the number of milliequivalents of Calcium and Magnesium together and multiplying by 50 gives the hardness as milliequivalents per liter of CaCO3.

(Ca (ppm)/20 + Mg (ppm)/12.1) x 50 = Total Hardness as CaCO3

These operations are summarized in the following table.

Table 13 - Conversion Factors for Ion Concentrations

To Get

From

Do This

Ca (mEq/l)

Ca (ppm)

Divide by 20

Mg (mEq/l)

Mg (ppm)

Divide by 12.1

HCO3 (mEq/l)

HCO3 (ppm)

Divide by 61

CaCO3 (mEq/l)

CaCO3 (ppm)

Divide by 50

Ca (ppm)

Ca (mEq/l)

Multiply by 20

Ca (ppm)

Total Hardness as CaCO3

You Can't

Ca (ppm)

Ca Hardness as CaCO3

Divide by 50 and multiply by 20

Mg (ppm)

Mg (mEq/l)

Multiply by 12.1

Mg (ppm)

Total Hardness as CaCO3

You Can't

Mg (ppm)

Mg Hardness as CaCO3

Divide by 50 and multiply by 12.1

HCO3 (ppm)

Alkalinity as CaCO3

Divide by 50 and multiply by 61

Ca Hardness as CaCO3

Ca (ppm)

Divide by 20 and multiply by 50

Mg Hardness as CaCO3

Mg (ppm)

Divide by 12.1 and multiply by 50

Total Hardness as CaCO3

Ca as CaCO3 and Mg as CaCO3

Add them.

Alkalinity as CaCO3

HCO3 (ppm)

Divide by 61 and multiply by 50

Water pH
You would think that the pH of the water is important but actually it is not. It is the pH of the mash that is important, and that number is dependent on all of the ions we have been discussing. In fact, the ion concentrations are not relevant by themselves and it is not until the water is combined with a specific grain bill that the overall pH is determined, and it is that pH which affects the activity of the mash enzymes and the propensity for the extraction of astringent tannins from the grain husks.

Many brewers have made the mistake of trying to change the pH of their water with salts or acids to bring it to the mash pH range before adding the malts. You can do it that way if you have enough experience with a particular recipe to know what the mash pH will turn out to be; but it is like putting the cart before the horse. It is better to start the mash, check the pH with test paper and then make any additions you feel are necessary to bring the pH to the proper range. Most of the time adjustment won't be needed.

However, most people don't like to trust to luck or go through the trial and error of testing the mash pH with pH paper and adding salts to get the right pH. There is a way to estimate your mash pH before you start and this method is discussed in a section to follow, but first, let's look at how the grain bill affects the mash pH.

Previous Page Next Page
Understanding the Mash pH
15.0
What Kind of Water Do I Need?
15.1
Reading a Water Report
15.2
Balancing the Malts and Minerals
15.3
Residual Alkalinity and Mash pH
15.4
Using Salts for Brewing Water Adjustment
Real Beer Page

Buy the print edition
Appendix A - Using Hydrometers
Appendix B - Brewing Metallurgy
Appendix C - Chillers
Appendix D - Building a Mash/Lauter Tun
Appendix E - Metric Conversions
Appendix F - Recommended Reading

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All material copyright 1999, John Palmer