The Big Six Water Ions
When measuring our brewing water or adjusting it, there are six main ions dissolved in the water that affect the mash pH and brewing chemistry. Understanding these ions is crucial for achieving desired results and adjusting the water to fit a specific beer style.
If you want to measure the water regularly used for brewing, these are the ions you should focus on. There are several ways to determine the ion content of your water, such as local water reports, brewing test kits, or sending a sample to a lab.
These water ions are usually expressed in parts per million (ppm), which can also be represented as mg/L. Here are the six ions, along with the recommended ranges for brewing:
Copper Beer Brewing Equipment
Calcium (Ca)
[50-100 ppm] – Acidifies the mash and lowers the mash pH, which is generally desirable for lighter color beers. It also helps precipitate phosphates and improves beer stability. Calcium provides some structural support to the beer as well.
Bicarbonate (HCO3)
[0-250 ppm] or Alkalinity [0-200 ppm] – Strongly alkaline, it raises the mash pH, which is undesirable for lighter color beers. High levels can negatively impact cold break and result in excessive bitterness. Bicarbonate and alkalinity primarily contribute to mash pH balance, and excessive alkalinity should be avoided. You can convert bicarbonate to alkalinity using this equation: alkalinity = bicarbonate * 50 / 61.
Sulfate (SO4)
[50-250 ppm] – Enhances beer bitterness and slightly lightens color. Its primary role is to balance chloride and determine the sulfate/chloride ratio, which affects bitterness perception in the final beer.
Chloride (Cl)
[0-250 ppm] – Reduces bitterness perception and enhances maltiness in beer. Along with sulfate, chloride determines the sulfate/chloride ratio, influencing bitterness perception.
Sodium (Na)
[0-150 ppm] – Enhances sweetness and body in certain dark beers. Sodium does not significantly affect mash pH but is mainly used to provide roundness in darker beers.
Magnesium (Mg)
[10-40 ppm] – Plays an important role in fermentation as yeast requires it. Grains in the mash contribute about 100ppm of magnesium. However, recent studies suggest that high calcium levels may inhibit yeast’s access to magnesium. Therefore, it is important to have magnesium levels (water plus magnesium from the mash) higher than calcium to promote yeast health. Magnesium also has a minor impact on mash pH, but bicarbonate and sulfate overshadow its effect.
Hop Pellets
When considering the big six ions, I prefer to focus on the first four. Calcium and bicarbonate primarily influence mash pH and work in opposite directions. Therefore, these are the main factors to consider when determining the desired mash pH and making adjustments. Similarly, sulfate and chloride are paired together to determine the malt-hop perception in the finished beer based on the sulfate/chloride ratio. Sodium, providing structural support, is mainly adjusted for darker beers. Magnesium is essential for fermentation, so ensuring a small amount is available for yeast is important. However, as mentioned earlier, it is also necessary to consider calcium levels and add more magnesium if working with a high-calcium water profile.
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