Calcium Sulphate (Gypsum) 100g is a brewing water treatment additive used to compensate for water chemistry deficiencies in your brewing water. It raises sulphate levels, which can accentuate hop bitterness and dryness in ales, and is also used in sherry-style fermentation to improve clarity and flavour stability.
Add small amounts (1–2g per 23 litres) to your water before brewing. Test your water hardness first and use in conjunction with other water treatment salts. Use with Gervin GV12 Ale Yeast in hop-forward ales and bitters.