Provides essential minerals, trace nutrients and vitamins for yeast growth and metabolism during fermentation. Used to help start slow fermentation and to restart stuck ones. Add 0.4 g per litre (9 g per 23 litres) and stir gently. May cause foaming if added to an ongoing fermentation. 5 ml (one teaspoon) = approximately 3.7 g. Better choice than yeast nutrient which lacks some of the essential compounds needed to get sluggish yeast going.