Priming Calculator - which Temperature should I enter?

[WrkdbfGuy]

I'm going to be using the Brewer's Friend Priming Calculator to determine the right amount of Corn Sugar to prime with. But I'm unsure which temperature I should be entering into the calculator. Here's what's happened to get to here:

• Primary Fermentation: 5 gallons at 58°F for 3 weeks (Kolsch, with Wyeast 2565)
• Racked to Secondary for Cold Crash: 36°F for 2 weeks

BTW, my plan is to bottle condition for about 3 weeks at room temperature.

The fermenting was fully complete before racking for the cold crash. I'm thinking I should enter 58°F into the Calculator rather than 36°F, since no ferm. activity was taking place during secondary.

What do you think?

Bill

 

[peterj]

Yeah I'd go with 58F as well. Probably not much CO2 (if any) was being produced at 36F.

 

[huckbof]

These calculators use the temperature to calculate how much dissolved CO2 is in the beer at near atmospheric pressure (i.e carboy with an airlock)

https://www.homebrewtalk.com/showthread.php?t=152427

using the equation from the above thread

V = (P + 14.695)*(0.0181 + 0.090115*exp( (32-T)/43.11) ) - 0.00334

at 58F you had 0.94 volumes CO2 dissolved in the beer, which is in equilibrium with the CO2 in the headspace according to Henry's law. I think this equation assumes that only CO2 exists in the gaseous phase.

But then you racked it PRESUMABLY to another carboy full of air and then put an air lock on it. So you have lost virtually all of the headspace CO2 that was in the primary and now you will have air in the headspace of the secondary which contains 0.039% CO2 from the air plus CO2 that came out of the beer to re-establish an equilibrium, so now there is less CO2 in the beer at that temperature, assuming it is still 58F. If it warmed up a bit there would be even less dissolved CO2.

Now you cooled the beer down to 36F and the equation predicts 1.42 volumes CO2, but this is wrong because the beer can at best only reabsorb ALL of the CO2 in the headspace that came out of the beer when it was racked. There are no other sources of CO2 other than the little bit in air (assuming fermentation is complete).

So it is best to assume the 58F which is 0.94 volumes CO2 dissolved. Even that is an high estimate because you would have lost some CO2 to the atmosphere during racking and it is likely that your beer warmed up slightly if you racked it inside your domocile.

The amount of dissolved CO2 is factored in when calculating priming sugar amount. So the more dissolved CO2 there is, then less priming sugar is needed to reach your target Volumes of CO2. If you use 36F as your temp you would in effect be under-carbing your beer.

 

[rodwha]

My understanding was to enter the temp your beer was last sitting at. I've entered 73* as I ferment for 1 week at 64* and then pull it and set it out for 2 more weeks at room temp. Most of my beers seem slightly under carbed though. Maybe I ought to try entering 64* to see how it changes things.

 

[BigFloyd]

It's about dissolved CO2 in the beer being bottled. You use the highest temp that the beer saw during the fermentation process. In your case, that's 58*F.

If you're looking for an average drinking (not style-specific) amount of carbonation, shoot for 2.5-2.6 volumes of CO2 when using one of the calculators.

 

[C-Rider]

Never saw anything about temp to determine how much sugar. I use Beer Smith and it just tells me how much to use. Is there a temp setting I"m missing somewhere??

 

[rodwha]

I use Northern Brewer's calculator and it certainly does ask.

 

[WrkdbfGuy]

Thanks everyone. I entered 58° in the Brewers Friend calculator which is what I was pretty sure was right anyway, was just looking for verification. I ended up using 4.5 Oz. of Corn Sugar.

Everything's bottled up and now for the hard part. Waiting. There certainly seems to be a lot of that in this home brew thing.

Bill

 

[brewkinger]

I use Beer Smith and it just tells me how much to use. Is there a temp setting I"m missing somewhere??

There sure is. Don't feel bad, I missed it at first.

On the FERMENTATION tab in your recipe, next to the CARBONATION window.
There are 2 other thumbnails. The one that looks like a small red check mark is where you can adjust the temperature.
The other one (that looks like a disk) is how to save the profile.
While I am on topic, there is also an adjustment above that on the FERMENTATION type that you can record the temperature of the fermentation of a particular beer.

 

[WrkdbfGuy]

Never saw anything about temp to determine how much sugar. I use Beer Smith and it just tells me how much to use. Is there a temp setting I"m missing somewhere??

BeerSmith 2 has the temperature entry in the "Carbonation Profile" that you're using for your recipe.

Bill

 

[huckbof]

It's about dissolved CO2 in the beer being bottled. You use the highest temp that the beer saw during the fermentation process.

Unless the temperature dropped from the high point and CO2 was still being actively generated.

I think it should be the highest temp of the beer after CO2 generation is complete.

If say you fermented at 65F in your garage and it reached target FG, then if the temperature of the beer increased to 70F in your house, then you would use 70F in the calculator because the dissolved CO2 would have re-equilibrated at the higher temperature.

Assuming you don't artificially add more CO2 or rekick the fermentation. One could argue that theoretically CO2 generation never drops to zero at normal temps, but at some point you are no longer generating enough CO2 to appreciably change the volumes of CO2.

 

[C-Rider]

BeerSmith 2 has the temperature entry in the "Carbonation Profile" that you're using for your recipe.

Bill

Thanks Bill...I'll check that right now.

 

[C-Rider]

There sure is. Don't feel bad, I missed it at first.

On the FERMENTATION tab in your recipe, next to the CARBONATION window.
There are 2 other thumbnails. The one that looks like a small red check mark is where you can adjust the temperature.
The other one (that looks like a disk) is how to save the profile.
While I am on topic, there is also an adjustment above that on the FERMENTATION type that you can record the temperature of the fermentation of a particular beer.

Thanks, this would explain why my last three batches which were cold crashe and bottled at say 50*F wore slightly over carbed. Not enough to gush on opening, but if you waited about 30 seconds it would gush.

 

[brewkinger]

Thanks, this would explain why my last three batches which were cold crashe and bottled at say 50*F wore slightly over carbed. Not enough to gush on opening, but if you waited about 30 seconds it would gush.

Yup.. I had a whole batch do that exact thing. I chilled them for 2 weeks before drinking and still had to open 2 bottles every time that I wanted to get a full glass of beer.