This week I take a look at the role of the Calcium ion in your beer brewing water and how it affects the structure of your beer.

Calcium plays an interesting role in brewing. First and foremost, it does acidify the mash, driving the pH down which is typically needed for many lighter beers where the mash pH would otherwise be too high. Therefore moderately high levels of calcium are used in many IPAs and lighter colored beers. Calcium also enhances the beer in other ways by promoting the precipitation of phosphates from the malt aiding in the stability of the finished beer.

However, calcium also plays an interesting but often overlooked role in providing structure to beer. A beer with little to no calcium (

There has been a trend in recent years to start with Reverse Osmosis (RO) water and build water profiles up using high levels of calcium, especially for IPAs. However recent research indicates that using too much calcium may actually be detrimental. The problem with very high calcium levels is that calcium can block yeast access to Magnesium, and magnesium is important for yeast growth. Many brewers working from RO water did not add any magnesium assuming the yeast could get enough magnesium from the malt.

So if you plan to use a high level of calcium in your finished beer you also need to evaluate the magnesium levels used. A good rule of thumb is that the total magnesium should be higher than the total calcium. To determine the magnesium level, start with the water’s magnesium ion level and add appoximately 100 ppm for magnesium that comes from the malt. In general the total magnesium (including malt) should be equal to or higher than the total calcium ion in your water.

I’m personally a fan of calcium, as I like to brew large dark beers that stand up well with the extra structure. As I mentioned it is very widely used in IPA brewing as well. However, before you dump a ton of calcium into your RO water, consider the level of structure you really need to support the beer, and also make sure you add some magnesium to help offset the high calcium levels.

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