Gypsum (Calcium Sulfate)
If you have soft water and are brewing a hop forward beer, you’ll want some Gypsum on hand. Gypsum (calcium sulfate) is used to add permanent hardness to your brewing water in the form of calcium ions, which will increase the hop perception in your beer.
(choose calcium chloride if you do not want sulfates in your beer)
Use 1-2 teaspoons of Gypsum for each 5 gallons of water