Gypsum (calcium sulfate) additive is used in the distilling and brewing community to put calcium ions back into distilled or reverse osmosis purified water. Can also be used to lower pH of water, wort, or mash. Used in de-mineralized or soft to medium hard water to increase permanent hardness. When used as directed, gypsum is effective in eliminating the variations of composition encountered in water from common surface sources. Establishing the proper pH of the mash and the wort and providing sufficient calcium ions essential for enzyme function, kettle protein coagulation and yeast metabolism.
In beer brewing, calcium sulfate gypsum is added to the brewing water to adjust the water chemistry and enhance hop flavor. In distilling, gypsum is added to the wash (the mixture of water, grains, and yeast used to produce spirits) to increase the ionic content, which can improve the flavors of the final product. However, the use of gypsum should be done in moderation, as too much can lead to an undesired taste.
Prepare a 1% solution of cold water and gypsum in a separate tank with vigorous mixing. Calcium salts are more soluble in cold water, and the hard mixing will help dissolve the salt more completely. Dilute the gypsum solution into water being heated for mashing or for sparging. The final concentration of salts should be in the range of 100 to 1000 ppm (mg/L). This will require 0.025 – 0.25 lb/Bbl (10 to 100 g/hl). If a tank is not available for making the solution ahead of time, the gypsum can be also added directly to the mash or sparge water with as much mixing as possible to disperse correctly.