We take another closer look at water chemistry as it applies to home brewing beer. This time, we create an experiment using water and calcium sulfate, also known as gypsum. The set up is just like our last brewing salts experiment, where we tasted water with different concentrations and discussed our thoughts. We also have a bonus experiment at the end.

Let’s go!

Gypsum Experiment Set Up

As we did with sodium chloride and calcium chloride, Gypsum was added to water so we could taste what that compound imparts in terms of flavor and mouthfeel.

We have a control of plain spring water. Then, we have samples with different concentrations:

  • 125 PPM
  • 250 PPM
  • 500 PPM
  • 1,000 PPM

With each taste, we describe what we think of the experience. Mostly, it wasn’t great.

The Outcomes

When we looked at the samples, it was clear that there is a solubility threshold between 500 PPM and 1,000 PPM.

It was clear because the water was not clear.

Here’s the list of our taste observations at different concentrations:

125 PPM: Not very perceptible
250 PPM: Chalky, slightly soapy
500 PPM: More pronounced chalkiness
1,000 PPM: Overwhelming, quite powdery

The main takeaway from this experiment and the last one is how much brewing salts you need to add to your beer. If you are looking to treat your water, you have to add enough brewing salts to get to over 125 PPM.

Mike states that if you are looking to dial in a Chloride to Sulfate ratio, the numbers need to be in the hundreds to make a difference.

Bonus Experiment – Epsom Salt

Mike made another solution – just one – with Epsom Salt (Magnesium Sulfate). Tested at a concentration of 1,000 PPM, this sample helped us compare to the calcium sulfate experiment. Surprisingly, even at the high end of our concentration level, the Epsom Salt has a minimal impact on taste. We’re not sure if we would add this brewing salt to more of our beers but the outcome was still interesting.