Help with Amount of Priming Sugar

[JeffersonJ]

I'm planning on bottling a Raspberry Brown Ale today and have a couple of questions about priming sugar calculations. I really made the beer for SWMBO. She tends to like beers with higher carbonation and I think it will fit with the style (in an almost fruit-lambic way).

This is also the first time I've cold-crashed. It's been at 40°F for three days.

So, I'm thinking of about 3.5 Volumes of CO2. The batch size is 5 gallons. It's been at 40°F for three days but fermented at 65°F. How much corn sugar should I use?

I used this calculator and input 3.5 Volumes and 5 gallons and 40°F:

http://www.tastybrew.com/calculators/priming.html

It gives me 5.5 oz of corn sugar. However, if I change the temperature to 65°F, it bumps it to over 7 oz. Can anyone provide some clarification? This has always been a confusing topic to me.

 

[cshamilton]

More CO2 stays in solution at colder temps, so you start with more when it is cold. That said if it was mostly in the 60s before cold crashing you already lost a lot of the CO2, however any CO2 in the head space could have redissolved. Did you rack to a secondary? If so there probably wasn't that much CO2 left and I'd shoot for the higher end of the sugar. If you left in primary the whole time - then go for the lower end. ALSO keep in mind that most glass bottles are rated at 3.5 volumes of pressure - so you need to be careful that you don't over do it. If it were me, I'd go for 5.5 to 6 oz for 5 gallons.

 

[JeffersonJ]

Thanks. I did transfer to secondary in order to add 4 lbs of raspberries (I typically just primary). And since there was some sugar in the fruit, there was a decent amount of fermentation going on in secondary.

 

[unionrdr]

In that case,it might be prudent to go with the temp in secondary.

 

[JuanMoore]

You'll want to use the highest temperature the beer reached after CO2 production stopped. If there was fermentation going on at 40°, and it never got any warmer afterwards, then use 40°. If you had it warmer for fermenting the fruit, and then cold crashed it, use the warmer temp. As mentioned, the reason the temperature is needed is because how much residual CO2 stays in solution depends on temperature. Warming the beer up will cause the CO2 to come out of solution, but cooling it down doesn't cause the beer to absorb or create any additional CO2.

 

[JeffersonJ]

Thanks for the advice guys - it makes more sense to me now.

It finished fermenting at 65°F and then I cold-crashed it. Even still, I'm wary of adding 7 oz of cane sugar as that calculator recommends. I think I'm going to stick to 6 oz.