# Bottling priming calculators: fermentation temp and sugar required

### Help Support Homebrew Talk:

#### DeanRIowa

##### Well-Known Member
Many of the Priming sugar calculators ask for the fermentation temperature to figure the required amount of sugar for desired CO2 volume levels. This is pretty straight forward for my ales since I do a constant fermentation temperature, but for lagers I wondered what temperature I should enter for the example below?

My current lager wort schedule:
52° F - 2 weeks
66° F - 5 days
35° F - 4 weeks

I usually bring my carboy into kitchen the night before bottling(66° F, 12 hours). I could avoid this step, but habit.

In this example above what temperature should I put into the calculator?

thank you,
Dean

Note: Kegging is not in my current future.

#### D.B.Moody

##### Well-Known Member
The calculator is asking for the temperature you will keep your filled bottles at while they carbonate. The temperature after you add the priming sugar. They are talking about the fermentation that produces the CO2 for carbonation, not the fermentation schedule you cited.
By the way, once the yeast is pitched it is beer.

EDIT: @GoodTruble's post below makes me edit after to when, and delete the struck part to estimate CO2 in the beer before priming sugar and capping. Sounds like you need the temperature when they're capped. But I don't see what prior unsealed fermentation temperature has to do with it.

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#### Miraculix

##### Well-Known Member
The temperature plays a role because the lower the temperature, the higher the amount of co2 that stayed in solution. The higher the temperature, the more of it gassed out and left through the air lock.

But as it has been said already, the current temperature is what counts, meaning the temperature of the liquid when you are bottling.

#### GoodTruble

##### Supporting Member
HBT Supporter
Wait. Once sealed in the bottle, all the CO2 from priming sugar will remain in the bottle. I thought the point of including temperature in the priming calculation was to estimate the amount of CO2 already present in the beer, and therefore, you were supposed to use the average temperature during primary fermentation. No?

#### Miraculix

##### Well-Known Member
Wait. Once sealed in the bottle, all the CO2 from priming sugar will remain in the bottle. I thought the point of including temperature in the priming calculation was to estimate the amount of CO2 already present in the beer, and therefore, you were supposed to use the average temperature during primary fermentation. No?
If you heat it up after primary, for example after cold lager fermentation, a lot of the co2 that has been kept in solution by the cold, will go out of solution. So there's no point in using the average. The liquid is usually saturated with co2 anyway, it's just that the amount of co2 necessary to saturate the same amount of liquid is higher at lower temperatures. So there's more co2 present when the solution is cold. Once temperature rises, co2 leaves the solution as gas.

Time might play a role, I don't know if this happens instantly.

#### GoodTruble

##### Supporting Member
HBT Supporter
Well, I don't want to suggest I know anymore than I do. The priming calculator I use(d) is Brewer's Friend..... (I actually now just default to 1 tbl per quart to get plenty of carb, bordering on over-carb).....

And they include this very vague, wandering
statement on this point......

"* Temperature of Beer used for computing dissolved CO2:
The beer you are about to package already contains some CO2 since it is a naturally occurring byproduct of fermentation. The amount is temperature dependent. The temperature to enter is usually the fermentation temperature of the beer, but might also be the current temperature of the beer. If the fermentation temperature and the current beer temperature are the same life is simple.

However, if the beer was cold crashed, or put through a diacetyl rest, or the temperature changed for some other reason... you will need to use your judgment to decide which temperature is most representative. During cold crashing, some of the CO2 in the head space will go back into the beer. If you cold crashed for a very long time this may represent a significant increase in dissolved CO2. There is a lot of online debate about this and the internet is thin on concrete answers backed by research. We are open to improving the calculator so please let us know of any sources that clarify this point."

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#### hotbeer

##### Opinionated Newb
HBT Supporter
I've only cold crashed twice, so I only have two experiences that might have been different for other reasons.

My first cold crash I used the amount of priming sugar I did for the previous batch that wasn't cold crashed without consulting a priming calculator. It carb'd pretty much as desired.

The second time I cold crashed, I used the current temp of the beer which was around 40°F and used the calculator. Which produced a way lower priming sugar requirement and a way under carbonated beer.

I can't help but think that calculators are either more suited to lagers or maybe pressure fermented beers. However in reality, they probably were made with some assumptions that don't always apply.

Since I don't cold crash anymore, I don't have to worry. But I've been using a little more sugar than the calculators suggest for ales and IPA's. I like my carbonation to last till I'm finished with the glass of beer. Not peter out in the first ten minutes.

#### DBhomebrew

##### Well-Known Member
I've only cold crashed twice, so I only have two experiences that might have been different for other reasons.

My first cold crash I used the amount of priming sugar I did for the previous batch that wasn't cold crashed without consulting a priming calculator. It carb'd pretty much as desired.

The second time I cold crashed, I used the current temp of the beer which was around 40°F and used the calculator. Which produced a way lower priming sugar requirement and a way under carbonated beer.

I can't help but think that calculators are either more suited to lagers or maybe pressure fermented beers. However in reality, they probably were made with some assumptions that don't always apply.

I don't follow how you got to your conclusions here. But your two experiences with cold crashing and which temp to put into the calculator speaks directly to Brewer's Friend's note.

During cold crashing, some of the CO2 in the head space will go back into the beer. If you cold crashed for a very long time this may represent a significant increase in dissolved CO2. There is a lot of online debate about this and the internet is thin on concrete answers backed by research.

Your anecdotal evidence should lead you to choose the warmest temperature post end of active fermentation. It's what I use, too.

#### hotbeer

##### Opinionated Newb
HBT Supporter
Essentially the two batches were identical in SG and quantity. Both using agave nectar for the priming sugar which is roughly the same as corn syrup.

The first batch had 38 grams of sugar added and the second 25 grams.

Though for the second batch I probably was looking at several calculators and noticed the ambiguity between what several stated the temp used should be from.

So from my little experience, I too would just use the overall temp the beer was fermented at or it's current temp whichever is higher.

Though the caveats in the Brewer's friends notes need consideration. For the most part if one has a bad result, it won't be the end of the world and doubtful it'll be disastrous. Maybe just messy at the worst.

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