In beermaking: Chalk. Sometimes used for temporary hardness in dark beers. Adjusts pH up.
In winemaking: Used to lower acidity levels. 2.5 grams per gallon will roughly lower acidity by .1%. It does not require cold stabilization to precipitate-out acid like Potassium Carbonate does, but it takes longer, affects flavor, and it reduces tartaric before dropping out malic or citric acids. See AD640 for Potassium Carbonate.
A rough approximate of weight is 1 tsp = 2.7 grams. We highly recommend using a scale to weigh the product for an accurate dose. We do not recommend relying on these rough conversions for accurate dosage rates.