While some people enjoy their hard ciders still or without much noticeable carbonation, others enjoy some bubbles or even sparkling. The fermentation process under open atmospheric conditions at 21C (70F) will naturally have around 0.85 volumes CO2. You may remember from my Mālus Trivium on Volumes CO2 that the 0.85 means you would have CO2 suspended or dissolved in your cider at approximately 85% of the volume of cider you have. Many hard ciders will have 2.0-3.0 volumes CO2. If you want this level of carbonation or more, you will need to either add sugar or bottle while the cider still has some residual sugar and is fermenting. The above graphic shows you the key numbers associated with creating carbonation.
If you have a gallon of hard cider and want 2.5 volumes CO2, you would need to add almost 27 grams of sugar to create the 1.65 volumes CO2 you need (0.85+1.65=2.5). If you are trying to use the natural sugar from your juice to create the 1.65 volumes CO2, you would need to bottle when you still have almost 0.003 or three points of natural sugars remaining. Check out my carbonation tips page for more detail on how to carbonate your ciders. However, as shown in the above graphic, it’s about a few key numbers that are good to remember: 1/2.6/0.6. Every 1 point of gravity has 2.6 grams of sugar per liter that generates 0.6 volumes CO2. Once you know this, you can quickly scale up to achieve any desire carbonation level desired. Remember 1/2.6/0.6 and you readily know how much sugar is needed to achieve your desired carbonation level.
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