Degassing and Priming Sugar Amount

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Jun 25, 2020
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I have started using the All in One Wine Pump, which automatically degasses the cider as I rack and bottle. My last batch of cider is less carbonated than earlier batches that used a gravity siphon, even though I added the same amount of sugar. So apparently I need to add extra priming sugar to account for the CO2 that is removed by the vacuum pump during racking and bottling.

Two priming sugar calculators that I looked at take pre-existing CO2 into account when calculating the priming sugar:
* Beer Priming Sugar Calculator | Brewer's Friend
* Homebrew Priming Sugar Calculator
The first one explicitly states the assumed amount of CO2 based on temperature. For 68 degrees F it is 0.86 volumes of CO2. But the amount of existing CO2 will be less than that due to the vacuum pump. I think that if I want 2.5 volumes of CO2 I would need to add the sugar for at least 3.0 volumes to account for the CO2 removed by the vacuum pump.

Sorry for the long winded explanation, but I was wondering if anyone else has encountered this issue. I'm not sure how much CO2 is left after using the vacuum pump, but it seems that I need to increase my target volumes of CO2 by at least 0.5.


Ale's What Cures You!
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Jun 4, 2006
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UP/Snowbird in Florida
I don't really know- but that seems about right. What you could do is play with the calculator so that you can raise the temperature high enough to have very little residual co2 in the calculator and see how much it recommends for a normal carb level. I don't know how much you're using now, but I'd probably go with 5.5 ounces (by weight) of priming sugar for a 5 gallon batch to start.