The Big Six Water Ions and Water Chemistry in Beer Brewing

by Brad Smith on August 6, 2021 · 5 comments

This week I take a look at the big six water ions in your water profile that drive the water chemistry of beer brewing.

The Big Six Water Ions

When we measure our starting brewing water or adjust our water, there are six main ions dissolved in the water that drive the mash pH as well as the brewing chemistry. Understanding these ions is critical for achieving the results you want as well as how to adjust your water to fit a particular style or type of beer.

If you are looking to measure the water you regularly use for brewing, these are also the ions you want to measure. There are several ways to find out the ion content of your water, including local water reports, brewing test kits or by sending a sample off to a lab.

These water ions are typically listed in parts per million (ppm) though you may also see them as mg/L which is the same thing. Here are the six along with the recommended ranges to use for brewing.

  • Calcium (Ca) [50-100 ppm] – Acidifies the mash and drives down the mash pH which is generally a good thing in lighter color beers. It also aids in precipitating phosphates and improving the stability of the beer. Calcium also provides some structure to the beer and is used in that role as well.
  • Bicarbonate (HCO3) [0-250 ppm] or Alkalinity [0-200 ppm] – Strongly alkaline so it will raise the mash pH which is undesirable in lighter color beers. High levels also will impede the cold break and emphasize bitterness in a harsh way. The main role for these ions is in mash pH balance, and too much alkalinity can be undesirable. You can convert from bicarbonate to alkalinity using this equation: alkalinity = bicarbonate * 50 / 61.
  • Sulfate (SO4) [50-250 ppm] – Suilfate enhances bitterness in beer and slightly lightens color. Its primarily role is as a counterbalance to chloride in determining the sulfate/chloride ratio which affects bitterness perception in the final beer.
  • Chloride (Cl) [0-250 ppm] – Chloride will lower the bitterness perception and enhance the maltiness of the beer. Its major role, along with sulfate, is in determining the sulfate/chloride ratio which affects bitterness perception in the beer.
  • Sodium (Na) [0-150 ppm] – Sodium provides enhances the sweetness and body in certain dark beers. However it is not a major player in mash pH so it is primarily used to provide some roundness in darker beers.
  • Magnesium (Mg) [10-40 ppm] – Magnesium plays an important role in fermentation as it is needed by yeast, but grains in the mash do provide about 100ppm of magnesium. However, recent research indicates that calcium may actually block the yeast’s access to magnesium if it is very high. So it may be important to keep the total magnesium levels (water plus magnesium from the mash) above the calcium to enhance yeast health. Magnesium also plays a small role in mash pH, but is largely overshadowed by bicarbonate and sulfate.

When looking at the big six ions, I prefer to pair the first four. Calcium and bicarbonate primarily affect mash pH and they work in opposite directions, so I focus on these when looking at where my mash pH should fall and how I might need to adjust it. Similarly I pair together sulfate and chloride and look at the sulfate/chlrodie ratio to determine the malt-hop perception in the finished beer. Sodium, which provides structure, is something I adjust mainly for darker beers. Magnesium is important for fermentation, so I make sure I have at least a small amount available for yeast, though as mentioned above you also want to consider calcium levels and add more magnesium if you are working with a high calcium profile.

I hope you enjoyed this week’s article from the BeerSmith Home Brewing Blog. Please subscribe for regular weekly delivery, and don’t hesitate to leave a comment or send this article to a friend.

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{ 5 comments… read them below or add one }

JOHN CAMPBELL August 8, 2021 at 3:38 am

Nice quick overview of water chemistry. Like many Beersmith software users I also use Bru’nwater. As long as I have used both programs the unadjusted mash pH in Beersmith has been consistently higher than that in Bru’nwater by about .05 units. In itself not anything to be concerned with as they are both estimates anyway. Recently I noticed that the Ca and Cl composition of the water is also lower in Beersmith. Being the obsessed person I am I started to look closer at the data/switches that we users had to set in both tools. Here is what I found. In Bru’nwater there is a field on the water adjustment page that wants to know what form of CaCl2 you are using. In my case and probably most others the answer to that is anhydrous. The other choices are dihydrate and solution. If I toggle my choice to dihydrate then the Ca and Cl levels are virtually identical in both programs. I’m okay with how Beersmith works because I understand what is causing the difference and I now know not to look to closely at the Beersmith sulfate:chloride ratio I just go to Bru’nwater for that. Maybe this could be a possible improvement in future versions of Beersmith.

Brad Smith August 10, 2021 at 4:15 pm

The main difference is the acid models and version 3.1 and 3.2 both have the option to select an acid model (called the BW model in BeerSmith) for your recipe in the equipment profile or on the mash page that is similar to the BNW model.

Moses M ogotsi August 23, 2021 at 8:12 am

I’m very interested in Brad Smith comments and his insightful guest, who bring in experience
and informative subjects.

lametcalf August 24, 2021 at 5:35 am

Thank you for this article. My husband has been brewing beer at home for about six months, and he is now very deep into the whole subject.

lametcalf September 2, 2021 at 5:45 am


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