Precipitated Chalk (calcium carbonate) is used to reduce excess acidity in wines. When added to an over-acid wine or must, it reacts with the acid to produce CO2 gas and calcium salts, effectively neutralising some of the acid and bringing the wine into better balance. Use carefully and in small amounts to avoid over-correction.
Add approximately 2.5g per litre to reduce acidity noticeably. Stir well and allow the foaming to subside before proceeding. Use alongside Tartaric Acid for fine-tuning wine acidity, and Yeast Nutrient to support healthy fermentation. See also: Citric Acid and Pectolase.