Gypsum- 1 lb. Go to amazon.com Related posts The 10 best autoclave tape 2022 FeatureAdds hardness to soft water when Brewing1 teaspoon of gypsum for 5 gallonsWhen using distilled water for Brewing, gypsum adds hardness to the water DescriptionIt increases calcium and sulfite levels in Soft water, increases acidity, and helps to settle proteins during the boil.