A 100g tub of Calcium Sulphate Gypsum by Almost Off Grid. Calcium Sulphate is also known as Gypsum or E516. It compensates for water deficiencies when homebrewing beers by lowering the water pH. It helps to protect against infection by adding essential minerals to the brewing water. It can also help sherry fermentation. It does come up occasionally in wine recipes, but it is used more often in beer making How to use: 1 oz per gallon of liquid. Add to first stage of fermentation and stir twice daily for 2-3 days.