Here’s what we test to find:
- Calcium (Ca2+)
- Magnesium (Mg2+)
- Sodium (Na1+)
- Carbonate (HCO3–)
- Sulfate (SO4-)
- Cloride (Cl-)
- Total Dissolved Solids
Calcium: Calcium is the principal mineral of hardness, having come from the water’s passage over limestone, dolomite, gypsum or calcified gypsiferous shale. Calcium increases mash acidity and inverts malt phosphate.
In appropriate amounts, calcium is advantageous to the brew. It stimulates enzyme activity and improves protein digestion, stablizes the alpha amylase, helps gelatinize starch and improves lauter runoff. Calcium also extracts fine bittering principles of the hop and reduces wort color. A calcium precipitate formed with potassium phosphate improves hot-break flocculation. It is also an essential part of yeast-cell composition; small amounts of calcium neutralize substances toxic to yeast such as peptone and lecithin. During aging, it improves clarification, stability, and flavor of the finished beer.
In excess, however, calcium precipitation with organic phosphates interferes with runoff filtering and robs the wort of phosphate, a necessary yeast nutrient. Calcium levels are usually 5 to 200 ppm; its solubility is greatly affected by the anions in solution with it.
Magnesium: Magnesium is the secondary mineral of hardness. It is essential as a co-factor for some enzymes and as a yeast nutrient. In small concentrations of 10 to 30 ppm, it accentuates the beer’s flavor, but it imparts an astringent bitterness when it is present in excess. Over 125 ppm it is cathartic and diuretic. Usually found at levels of 2 to 50 ppm, its solubility is less affected by carbonate anions in solution than is calcium.
Sodium: The sour, salty taste of sodium accentuates beer’s flavor when it is found in reasonable concentrations. It is poisonous to yeast and harsh tasting when it is in excess. Usually found at levels of 2 to 100 ppm, it is very soluble.
Carbonate: Carbonate is a strongly alkaline buffer formed by the reaction of atmospheric carbon dioxide with hydroxides of alkaline-earth and alkali metals. Carbonates go into solution as hydrogen carbonates (HCO3-, "bicarbonates"), which are strong buffers. Bicarbonates form by the reaction of a carbonate ion with a molecule each of carbon dioxide and water.
Carbonates resist increases in mash acidity by neutralizing acids as they are formed. It also hinders gelantinization of starch by alpha amylase, impedes trub flocculation during the cold break, and increases risk of contamination in the ferment. It contributes a harsh, bitter flavor overwhelming in delicate lagers, and carbonate in excess of 200 ppm is tolerable only when a dark-roasted malt is used to buffer its excessive acidity. Preferably, carbonate should be less than 50 ppm when pale malt or infusion mashing is used.
Sulfate: Sulfate is weakly basic, and its alkalinity is overcome by most acids. It is fairly soluble. It gives beer a dry, fuller flavor, although the taste is somewhat sharp. With sodium and magnesium it is cathartic. Above 500 ppm it is strongly bitter and levels are best kept less than 150 ppm.
Chloride: Chloride is very weakly basic and readily neutralized. It accentuates bitterness, increases stability of any solution, and improves clarity. The "salt" taste of chloride generally enhances beer flavor and palate fullness, but the salt flavor can be reduced with calcium and magnesium. Usually found at levels of 1 to 100 ppm, chloride levels should never by more than 100 ppm for light beers and 350 ppm for beers above 12 degrees Balling (SG of 1.049).