Gypsum (Calcium Sulphate) is used to harden water and to lower pH. Use in the brewing mash to adjust water hardness.
Usage 1 to 2 teaspoons for 5 gallons.
There are approximately 10 teaspoons per ounce.
Available in 2 oz, 8 oz & 1 lb sizes, packaged in a re-sealable zip bag.