Add 1 tsp to water prior to fermentation, to replicate the natural hard water supply when making English Ales etc. 1 tsp. of Epsom Salt (MgSO4) in 20 litres of water will increase concentration of (Mg++)ion 52ppm (SO4--)ion. 207ppm.
Irish Moss is a clarifier and is used to clear protein during the boil when mash brewing. Add one teaspoon per 20L of wort, 10 min before the end of the boil.
Used for making drier, lower carb beer styles. Add with the yeast to break down more of the malt sugars which allows the yeast to ferment them for a lower carb, drier beer. This enzyme may extend fermentation time so ensure the specific gravity is stable for 3 days prior to bottling.