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CALCIUM CARBONATE CaCO3     Instructions

Fall Bright, The Winemakers Shoppe
www.fallbright.comDundee, NY, USA, 607-292-3995

(for juice BEFORE fermentation)


NOTE: Acid reduction with Calcium Carbonate, Potassium Bicarbonate, OR Acidex can not exceed more than a .4% total reduction either by combined or any one application.

Note: There are 28.3495 grams per ounce. One ounce is ~12 1/2 teaspoons, there are 3 teaspoons in 1 tablespoon.  

Approximately 2.5 grams of CaCO3 will reduce the acidity of 1 gallon by 0.1%


CaCO3 .3-.4 grams /liter will increase the pH by ~ 0.1 This shift must be taken into consideration and is the restriction in the use of CaCO3 and the other acid reduction aids noted above. The pH shift will vary depending on the chemistry of the must.  


With a initial pH of 2.95, the addition of .3 grams/liter being equivalent to 1.13 grams/gallon (1 gallon = 3.78 liter), at the rate of 2.5 grams per gallon, will shift the pH by ~.22 resulting in a pH of around 3.17. If you have a pH meter, put it to use during any acid reduction using these additives. Do not go above a pH of 3.5; 3.4 is better for a maximum pH. 


As CaCo3 reduces tartaric acid first (by producing calcium tartrate), it is important to treat only a portion or one third of the total volume of juice. When fermenting on the skins, you will be able to draw off approximately 1/3 of the anticipated juice volume after 2 days of fermentation. Treat this portion with the total amount calculated to reduce the entire final volume. To calculate the amount needed for reduction:


1. Reduce the initial acid reading by .12 to allow for acid reduction during fermentation OR by .20 to allow for combined reduction due to fermentation and cold stabilization. (Cold stabilization is highly recommended.) This figure is the “potential natural acidity.” 

2. From the potential natural acidity subtract the desired total acidity. This depends on your taste. However, never go below .6 or the stability will be affected. This will yield the acidity to be neutralized by the calcium carbonate. 

3. If the acidity to be neutralized is greater than .4, use the lower figure. Do not adjust more than .4%. You may want to consider the use of sugar water (10-15%) and or blending with a lower acid juice.  

4. If the reduction is .4% and 2.5 grams will reduce the acidity of 1 gallon by 0.1%, the amount required will be 2.5 x 4 or 10 grams per gallon times the number of gallons, i.e. 5gallons (times) X 10 = 50 grams for 5 gallons. Add this amount to 1/3 of the entire volume. This will strip most of the acids from this portion.

· Add this amount of calcium carbonate slowly, over a period of 1 hour with frequent agitation. 

· Allow this to settle for 24 hours and rack, adding back into the total volume. This helps to prevent excessive distortion of the entire natural acid profile. 


Ferment as desired, racking 3-4 times. *Calcium tartrate is not stabilized by cold. In fact these crystals grow better at warmer temperatures around 60o F. To protect against late Calcium Tartrate formation in the bottle, filter a wine and let it sit for 4-6 weeks and then bottle, sterile filtering if necessary. 


Reference:Home Winemaking Step by Step, J Iverson, Tom and Marcy Mitchell, *Thomas Henick-Kling, Associate Professor Cornell U


May Your Wines Fall Bright!