# Amount Of Bulk Priming Sugar For A Regular 23l Run



## michael_aussie (23/5/10)

I've search here for the past hour or so, and haven't got a clear answer.
One poster in a thread talked about using 100 gm.
Another poster said they used 120 gm.
A third gave a link to an external site that wanted to know all sorts of information that i didn't know.

I am intending to have my first go at bulk priming.

How much sugar should I use?

In hind sight, should I have only filled the drum to 22 litres? 
Now that I already have 23 litres, whatever I dissolve the suger in will mean I now have too much water.

Michael


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## kelbygreen (23/5/10)

best method is to use this calculator. LINK

down the bottom has beer styles and will tell you the C02 for that style, so pick your style or just leave it as general. Beer temp is the the highest temp while fermenting. Beer volume is the volume you will be priming. and just pick the sugar you are using and hit calculate.


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## RdeVjun (23/5/10)

OK, what's the style, i.e. is it an ESB, an APA or a Dortmunder Export etc.? That will guide you in the level of carbonation for the style you're bottling, and what's the maximum temperature during fermentation? That plus the volume and type of sugar you're using will tell you how much sugar to add. 

Here's one, all the defaults are imperial though, but easy enough to change everything to metric. Handy article.

Don't panic if you're off by a litre or two, the calculators are volume- based and it is only a guide anyway. I do hate bottling but I love bulk priming.


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## barls (23/5/10)

kelbygreen said:


> best method is to use this calculator. LINK
> 
> down the bottom has beer styles and will tell you the C02 for that style, so pick your style or just leave it as general. Beer temp is the the highest temp while fermenting. Beer volume is the volume you will be priming. and just pick the sugar you are using and hit calculate.


hate to burst your bubble but the temp would be the current temp of the beer being bottled so to figure out how much residual co2 is in solution.
good calculator i use to have this one but lost the link over time


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## michael_aussie (23/5/10)

Thankyou for your prompt replies.
Based on that link I need to add around 190 grams.
I was happy to see that the amount only varied by about 5 gm if I used 20 degrees instead of 22 degrees.


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## boobiedazzler (23/5/10)

I always worked on the theory that priming calculations were worked out using the fermentation temperature.


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## boobiedazzler (23/5/10)

190 grams sounds like a hell of a lot for your batch size


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## themonkeysback (23/5/10)

barls said:


> hate to burst your bubble but the temp would be the current temp of the beer being bottled so to figure out how much residual co2 is in solution.
> good calculator i use to have this one but lost the link over time



I would have thought that highest temp was right. If your bottling temp is higher than your ferment temp, then what you are saying makes since, but if you cool you beer after fermenting it will not increase the amount of CO2 within the beer.

Adam.


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## clarkey7 (23/5/10)

michael_aussie said:


> Thankyou for your prompt replies.
> Based on that link I need to add around 190 grams.
> I was happy to see that the amount only varied by about 5 gm if I used 20 degrees instead of 22 degrees.


Make sure it has completely fermented out ....3 volumes is a lot so you don't want any extra fizz......It'll be spritzy.....
PB


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## themonkeysback (23/5/10)

michael_aussie said:


> Thankyou for your prompt replies.
> Based on that link I need to add around 190 grams.
> I was happy to see that the amount only varied by about 5 gm if I used 20 degrees instead of 22 degrees.



For your first crack at bulk priming I would err on the side of slightly less priming sugar rather than more. Instead of 3 volumes of CO2 I would go for somewhere between 2 and 2.5 volumes CO2. Better to have slightly less carbonated beer than bottle bombs.

Adam.


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## manticle (23/5/10)

barls said:


> hate to burst your bubble but the temp would be the current temp of the beer being bottled so to figure out how much residual co2 is in solution.
> good calculator i use to have this one but lost the link over time




My understanding is highest temp after primary fermentation. If that is when it is being bottled then the temp at bottling is correct. If you cold condition and bottle while it's cold but it reached 22 for a day or so in secondary then 22 is the temp.

I have scratched my head over this many times so if someone could clear it up once and for all it would be superb


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## themonkeysback (23/5/10)

manticle said:


> My understanding is highest temp after primary fermentation. If that is when it is being bottled then the temp at bottling is correct. If you cold condition and bottle while it's cold but it reached 22 for a day or so in secondary then 22 is the temp.



Don't think I can clear it up "once and for all", but unless there is some sort of positive pressure involved after you cool the beer - hence forcing CO2 back into the beer, I would think this ^ is correct.

Adam.


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## barls (23/5/10)

ok if you ferment at 18 degrees and then cold condition, the beer will absorb co2 while cold conditioning. The dissolved co2 will stay in solution till its warmed up.
Where as if you ferment at 18 then bottle it will have less dissolved co2 as it hasnt had the opportunity to absorb as much co2.
hence why its the current temp of the beer to be bottled and not the highest temp reached.
its the same principle as force carbing. the colder the liquid, the more that will be absorbed and stay in solution.


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## kelbygreen (23/5/10)

hmm ok. I was always unsure of it as well but read a thread few weeks back where all agreed that it was the highest temp not current temp. Now I am confused again lol but I currently havnt bulk primed yet but you it to work out roughly how much to put in each bottle. anyone else can shed some light on this (seems to be varied) discussion


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## Florian (23/5/10)

manticle said:


> My understanding is highest temp after primary fermentation. If that is when it is being bottled then the temp at bottling is correct. If you cold condition and bottle while it's cold but it reached 22 for a day or so in secondary then 22 is the temp.
> 
> I have scratched my head over this many times so if someone could clear it up once and for all it would be superb



I used to scratch my head too and therefore never bulk primed. But it seems that CO2 disappears when the beer gets warm, the warmer it gets, the more CO2 disappears. Therefore it needs to be the highest temp the beer has been since primary fermentation has significantly stopped. If you would raise the temp to 25 degrees while fermentation is still going like crazy and you then lower the temp to lets say 18 while ferment is till crazy than the 25 degrees would not count, as still plenty of CO2 is produced after it has been lost at 25.

So usually the temp to put into the calculator would be the one of your diacetyl rest if you're having one, or the ferment temp if you're brewing ales. I say usually, because obviously when you are fermenting an ale at 18, and then forget it on the bench for a few days in 35 degrees, then 35 will be your number (if the beer was out long enough to get to that temp).

Hope that makes sene.

Florian


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## themonkeysback (23/5/10)

barls said:


> ok if you ferment at 18 degrees and then cold condition, the beer will absorb co2 while cold conditioning. The dissolved co2 will stay in solution till its warmed up.
> Where as if you ferment at 18 then bottle it will have less dissolved co2 as it hasnt had the opportunity to absorb as much co2.
> hence why its the current temp of the beer to be bottled and not the highest temp reached.
> its the same principle as force carbing. the colder the liquid, the more that will be absorbed and stay in solution.



But during fermentation you will lose some CO2 from the fermenter, so even if you drop the temp to say 7 degrees, you will not end up with the same amount of CO2 within the beer as if you fermented at 7 degrees. 

Adam.


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## manticle (23/5/10)

barls said:


> ok if you ferment at 18 degrees and then cold condition, the beer will absorb co2 while cold conditioning. The dissolved co2 will stay in solution till its warmed up.
> Where as if you ferment at 18 then bottle it will have less dissolved co2 as it hasnt had the opportunity to absorb as much co2.
> hence why its the current temp of the beer to be bottled and not the highest temp reached.
> its the same principle as force carbing. the colder the liquid, the more that will be absorbed and stay in solution.




And when it warms up it comes out of solution yes?

So therefore if the brew hits 22 after primary ferment has done its thing, that CO2 will be lost, even if you cold condition down to 2 degrees and bottle between 2 and 4.


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## Florian (23/5/10)

barls said:


> ok if you ferment at 18 degrees and then cold condition, *the beer will absorb co2 while cold conditioning*. The dissolved co2 will stay in solution till its warmed up.
> Where as if you ferment at 18 then bottle it will have less dissolved co2 as it hasnt had the opportunity to absorb as much co2.
> hence why its the current temp of the beer to be bottled and not the highest temp reached.
> its the same principle as force carbing. the colder the liquid, the more that will be absorbed and stay in solution.


Sorry Barls, but this is not correct. 
The beer does not absorb any C02 while cold conditioning (after fermentation is finished). In fact, cold conditioning does not affect your residual C02 levels at all. Only warming the beer will make it loose C02. The beer can only absorb C02 during fermentation (or through pressure of course).

Here is a passage from an AHB article about bulk priming:

_So in an example of fermenting for 5 days at a constant 18C (with FG being stable for the last 48hrs), then being crash chilled;

The level of CO2 remaining at 18C is now stable, because you've given it enough time to confirm that fermentation has finished, which allows enough time to desaturate to the level it would normally be at for 18C. The chilling then does nothing in regard to the CO2. If you bottle at this point, then you would use 18C for your saturation level. 

If you warm the beer before bottling.......if it is warmed to any point under 18C, then 18C is still used. If it is warmed to a temperature over 18C, then the new temperature would be used...._

Hope that clears things up now. As said earlier, always use the warmest temperature the beer has ever been from a few days into fermentation til bottling. Obviously, if you expose a full fermenter to 35 degrees ambient temperature for an hour only, this will not affect the beer temperature as it needs more time to warm up completely.

Florian


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## theredone (23/5/10)

from my personal experience of late, i have been adding too much. dont get me wrong i do like a bit of fiz but i will be cutting down from 180 to maybe 150 for 23lt batches from now on


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## kelbygreen (23/5/10)

I use about 180g in 30 bottles. this is 23lts but I brew 25lts and get 30 bottles sometimes 31 at most and dont leave much liquid behind last bottle usually carbs in a week as so much yeast


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## michael_aussie (23/5/10)

Well I have finsihed bottling 3 runs. 
I used a round 200 gm in the end (ok, probably 210 gm).
Most were into PET bottles, so I'm not really concerned about bottle bombs.
And I love head.
I would far prefer too much head than not enough.
.
What I find slightly strange about all of this is, when I have put sugar in the bottles (I have been using 2 teaspoons per litre) the alternative was the Coopers drops. 1 per 375ml, 2 per 750ml. Obviously there is no scope for +/- adjustments with the drops.
What does a Coopers drop per stubbie work out as?


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## RdeVjun (23/5/10)

FWIW, I just primed 19L of RIS with just 66g of sugar for 1.8 volumes. Style is the real key IMO, so I pay more attention to the carbonation volumes for the particular style being bottled, while temperature is usually only a minor component.

If you play around with the temps, from one end of a realistic scale to the other (say an ale, so 15C to 22C), you'll see it makes SFA difference in the end. Eg. my RIS wanted 68g at 22C and 55g at 15C, so 13g difference, a maximum of 25% from ideal. Hardly worth losing sleep over, I'd say most drinkers wouldn't even notice a difference of that order...


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## warra48 (23/5/10)

3 volumes of CO2 is very high for my liking, and is right up there at the level for Hefeweizens.
You'd better be darn sure our brews are fully fermented out, as you'll get lots of bubbles at that level.

For a 23 litre batch of Mild, I've primed with as little as 80 gr of caster sugar, and they've been adequately carbonated.


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## michael_aussie (23/5/10)

warra48 said:


> 3 volumes of CO2 is very high for my liking, and is right up there at the level for Hefeweizens.



A few have said that 3 is very high.
I had no idea what to use, and only used 3 because the "tool" recommended 2.9-3.1 for 
homebrew general, which just about sums me up!


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## rendo (23/5/10)

michael_aussie said:


> A few have said that 3 is very high.
> I had no idea what to use, and only used 3 because the "tool" recommended 2.9-3.1 for
> homebrew general, which just about sums me up!



Mike,
dont stress.....it will be sweet. I love a reasonably well carbed beer, 200gm will rock it. I usually go between 180 - 220. Just be sure (as others have said) that fermentation has finished, otherwise there will be extra sugars, meaning extra CO2, meaning extra pressure, meaning possible kaboom-ies, but PET kaboomies are better than glass kaboom-ies. I always leave the beer in the ferm for at least a week after it has fermented, for a variety of reasons. Good practice generally ...(always exceptions)....

rendo


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## kelbygreen (23/5/10)

what style beer are you brewing?? As I say try work it out to actual volume not what volume is in the fermenter as you have 23lts but 2lts maybe trub. Why I brew 25lts I found I get the 30 bottles or 23lts out of that. so if you brewed 23lts you might only bottle 21lts.


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## michael_aussie (23/5/10)

rendo said:


> Mike,
> dont stress.....it will be sweet. I love a reasonably well carbed beer, 200gm will rock it. I usually go between 180 - 220. Just be sure (as others have said) that fermentation has finished, otherwise there will be extra sugars, meaning extra CO2, meaning extra pressure, meaning possible kaboom-ies, but PET kaboomies are better than glass kaboom-ies. I always leave the beer in the ferm for at least a week after it has fermented, for a variety of reasons. Good practice generally ...(always exceptions)....
> 
> rendo



ty rendo, that is reassuring.

kelbygreen, 
I have 3 kits that I bottled. They were all 21 days in the drum, and had final SGs of 1010 to 1012.
#13 B1 Coopers Dark Ale + Tooheys Liquid Brewing Sugar P2/5/2010 S23/5/10
#14 B2 Coopers Dark Ale + Tooheys Liquid Brewing Sugar P2/5/2010 S23/5/10
#15 B3 Brigalow Larger + 150gm Coopers Brewing Sugar P2/5/2010 S23/5/10



I found this link:
http://www.aussiehomebrewer.com/forum/inde...;showarticle=79

This gives a further explaination of the variables of the "tool" in particular the temperature to use.


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## Screwtop (24/5/10)

Examples:

22L of beer at 15 deg 125g sugar = carbonation level of 2.5 volumes (1.01 volumes of residual Co2 in the beer)
22L of beer at 22 deg 125g of sugar = carbonation level of 2.3 (0.81 volumes of residual Co2 in the beer)

Oh FFS - Now thats well worth worrying about eh! :lol: 

Screwy


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## Rod (24/5/10)

RdeVjun said:


> FWIW, I just primed 19L of RIS with just 66g of sugar for 1.8 volumes. Style is the real key IMO, so I pay more attention to the carbonation volumes for the particular style being bottled, while temperature is usually only a minor component.
> 
> If you play around with the temps, from one end of a realistic scale to the other (say an ale, so 15C to 22C), you'll see it makes SFA difference in the end. Eg. my RIS wanted 68g at 22C and 55g at 15C, so 13g difference, a maximum of 25% from ideal. Hardly worth losing sleep over, I'd say most drinkers wouldn't even notice a difference of that order...




I have just fermented an 23 litres of RIS , @18C 

SG 1091 FG 1028

see my thread

http://www.aussiehomebrewer.com/forum//ind...c=44615&hl=

using the calculator , for irish dry stout ( is this OK for an RIS ), it suggests 82g

I like a good head so was going to add 100g of dextrose , this would be a bit more than your addition which would be 82g for my 23 litre batch

how significant would the extra 18 g be 

probably more worried about bottle bombs 

is your RIS batch finished 

maybe 82g is the way to go 

your advise please


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## manticle (24/5/10)

Screwtop said:


> Examples:
> 
> 22L of beer at 15 deg 125g sugar = carbonation level of 2.5 volumes (1.01 volumes of residual Co2 in the beer)
> 22L of beer at 22 deg 125g of sugar = carbonation level of 2.3 (0.81 volumes of residual Co2 in the beer)
> ...




In those circumstances no it's not. But what if you cold condition or lager? Fair bit of difference between a beer at 20 degrees (around 145g for 2.5 vol in 22 litres) and a beer at 2 degrees (80g for the same vol). That is worth worrying about.

@Michael Aussie and others - don't confuse head with carbonation. Sure there's a connection but you can have fizzy beer that fails to hold a head and lightly carbonated beer that forms and holds a nice, dense creamy head. 4 vol won't necessarily give a better retained head than 1.9.


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## Rod (24/5/10)

manticle said:


> In those circumstances no it's not. But what if you cold condition or lager? Fair bit of difference between a beer at 20 degrees (around 145g for 2.5 vol in 22 litres) and a beer at 2 degrees (80g for the same vol). That is worth worrying about.
> 
> @Michael Aussie and others - don't confuse head with carbonation. Sure there's a connection but you can have fizzy beer that fails to hold a head and lightly carbonated beer that forms and holds a nice, dense creamy head. 4 vol won't necessarily give a better retained head than 1.9.



Manticle , 

I thought you might have answered my previous thread on priming Dan's RIS

will I be OK with 82g or should I use 100g


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## manticle (24/5/10)

I did partially answer it - head is not directly related to volumes of C02.

I'm not an RIS expert so take what I say with a grain of salt. It's what I would do in your situation.

First of all make sure it's finished. Then you don't need to worry about bottle bombs. Take a hydrometer sample tube full and put it in a stubby (clean but sanitised is unnecessary). Seal it and shake the crap out of it. Allow it to sit indoors where the temp might hit 20-30 degrees. After a couple of days, measure the gravity, reseal, shake and leave again for a few more days and see if the gravity has dropped. Once you get stable gravity you should have an idea of expected FG. If the FG in the fermenter is close to that then prime with whatever amount you like. 

Because you are ageing an RIS (presumably) you have a long time for carbonation to take place so low carb is not a bad thing (suits the style too). I think anything between 80 and 100 will be fine - if you are worried split the difference and use 90g.


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## barls (24/5/10)

here you go real science heres the graph




and the web page http://www.elmhurst.edu/~chm/vchembook/174temppres.html

so going by this the lower the temp the more co2 is absorbed at a lower pressure. therefore if your cold conditioning your beer sits under a layer of co2 right. at low temps its enough for this gas to be dissolved at room pressure. hence why its more important to be the current temp of the beer not the highest temp reached as i was explaining.

With this point below you make it sound impossible to force carb a beer. Hence by lowering the temp we can negate the need for a high pressure to speed up the absorption of co2.
what im saying is true you can get around this by simply warming the beer back to room temp after cold conditioning.
any way using my brewing program i get that you wanted to add 8.6 g per L to get the desired 3 volumes at 20 degrees beer temp
while at 10 degrees it drops to 7.3 g per L and at 0 its 5.1g per L. this is taking in to account of the dissolved CO2 in the beer. 


Florian said:


> Sorry Barls, but this is not correct.
> The beer does not absorb any C02 while cold conditioning (after fermentation is finished). In fact, cold conditioning does not affect your residual C02 levels at all. Only warming the beer will make it loose C02. The beer can only absorb C02 during fermentation (or through pressure of course).
> 
> Here is a passage from an AHB article about bulk priming:
> ...


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## RdeVjun (24/5/10)

Rod said:


> how significant would the extra 18 g be


Most likely not very significant. Don't lose sleep over it would be my advice as it won't be a show- stopper.


Rod said:


> probably more worried about bottle bombs


Precisely. I'm hardly a RIS specialist, so just like manticle, but I'd be sure that sucker is finished, that's why mine spent a few extra weeks at the end of the bottling queue. Sure enough, it dropped a couple of points in that time.


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## manticle (24/5/10)

@barls:

I'm still confused. The way I interpret what you're saying is that co2 will be dissolved back into solution at cold temps. However the co2 has to come from somewhere. If you leave a beer in secondary like I do for 3-7 days after FG is reached then where does that co2 come from? When I cold condition, my beer is flat and the co2 has dissipated.

Not trying to argue with you - I have an inkling you know much more about brewing than I.


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## barls (24/5/10)

it can come from the layer of co2 the beer is sitting under in the fermentor especially if you are using the same fermentor. as during fermentation this layer is not completely removed only vents off the excess from the co2 production during fermentation.
this is also one of the reasons why if you use a secondary, it can have very minimal head space as compared to a primary.
yeah i do know a little bit about this as im actually trained as a hydraulics and pneumatics tech.


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## Florian (24/5/10)

Barls, am not trying to argue either, just trying to understand it (which I thought I had). Picking up on Manticle's point, if I ferment in primary, then secondary and for traditions sake then transfer to a lagering vessel without head space, where would the C02 come from, when I do a D-Rest in secondary and then transfer warm to the lagering vessel? The way i understand it is that there then sholdn't be a C02 layer anymore, and therefore no C02 can dissolve into the beer.

This whole "which temperature to put in the priming calculator issue" used to bugger me quite a bit and I therefore searched for an answer. That's how I ended up on the AHB article which surprisingly says the exact opposite from what you say. Apart from what I quoted yesterday it also says: _ 5. Decrease in temperature, leading to the uptake of CO2 (This is also discarded, because as liquid cools it will reabsorb CO2, *but only if there is top pressure as well as a source of CO2*._

I am still not convinced, and am wondering two things: 
1.If you are right, then who wrote the AHB article?
2. If you would have a half full bucket of cold water, and would pump a layer of C02 onto it (even cover the whole thing with a lid if you like), would you then get soda water (lightly carbonated only) without applying any pressure to it? 

As I said, am not trying to argue and am happy to be corrected.

Florian


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## manticle (24/5/10)

barls said:


> it can come from the layer of co2 the beer is sitting under in the fermentor especially if you are using the same fermentor. as during fermentation this layer is not completely removed only vents off the excess from the co2 production during fermentation.
> this is also one of the reasons why if you use a secondary, it can have very minimal head space as compared to a primary.
> yeah i do know a little bit about this as im actually trained as a hydraulics and pneumatics tech.




My impression is that the co2 blanket has a finite life. How long does it last?

The reason I'm asking is because I cc all my beers and up until recently this question confused the hell out of me. Therefore I used to let everything warm to ambient before bottling so I didn't have to worry.

Recently however, someone suggested that warming will allow some compounds that have been dropped out by CC to go back into solution so I've started to bottle at the same temps as CC (or a few degrees warmer, allowing for bringing out of the fridge, priming and letting sit for 30 mins or so).


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## Florian (24/5/10)

manticle said:


> My impression is that the co2 blanket has a finite life. How long does it last?
> 
> The reason I'm asking is because I cc all my beers and up until recently this question confused the hell out of me. Therefore I used to let everything warm to ambient before bottling so I didn't have to worry.
> 
> Recently however, someone suggested that warming will allow some compounds that have been dropped out by CC to go back into solution so I've started to bottle at the same temps as CC (or a few degrees warmer, allowing for bringing out of the fridge, priming and letting sit for 30 mins or so).



Judging by that infamous AHB article you are right with bottling cold:

_So, if you are using a priming calculation that takes the residual CO2 into account, you are wasting time and energy, and possibly compromising your calculations, by warming your beer to ambient prior to priming and bottling. You may as well just get it straight out the fridge, and do it straight away. (You also have the benefit that you get less foaming when cold). The exception to this would be if you have had unstable temperature conditions during fermentation, and do not know what the temperature of your beer was at the end of fermentation._


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## barls (24/5/10)

i know your not trying to ague, just understand.
a couple of points i can address. 
1. if the co2 layer has a finite life what causes it disappear? in a sealed vessel its happy to sit on top of the beer till disturbed by some process or external influence or removed. co2 is heavier than air so it will always displace air.
2.every time you rack it decreases the amount of dissolved c02 in solution due to stirring motion of the racking process no matter how gentle. so using a primary, secondary and finally a lagering vessel you have already decreased the dissolved co2. thus creating a new co2 layer in the vessel, providing it hasnt been purged with co2 before filling.
3.the bucket of water will absorb co2 but only up to the limits of the current atmospheric pressure. so therefore it will never reach even a light spritzing of carbonation at room pressure. it will have a higher level of dissolved co2 than one that is at the same temp but without the layer of co2.

but you can see why i say its the current temp rather than the highest reached.
say you have two beers. both reach say 22 in fermenting. at this point they have the same level of dissolved co2 you then rack both in to two separate but the same size secondry/ lagering vessel. the co2 is reduced at this point but still close.
you take one and put it at 2 degrees and the other at room temp.
you leave them for 3 weeks the one thats been in the fridge will have a higher dissolved co2 level than the one that hasnt.
this needs to be taken in to account as with some styles it could mean the difference between hitting the right carb and completely overshooting it.


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## Screwtop (24/5/10)

barls said:


> yeah i do know a little bit about this as im actually trained as a hydraulics and pneumatics tech.




Good, will be interested to hear your take on this. 

We ferment some beer maybe with a closed fermenter and airlock, or maybe not. The fermentation temp has been 10C, we can calculate from a table the Co2 in solution at that temp. Then we reduce temp to 1C for cc'ing. The volume of the liquid reduces slightly, if the fermenter was left open during fermentation, or if the beer is racked to another vessel prior to cc'ing there will be no pressure in the vessel. If the temp is dropped in a closed fermenter with some head pressure (depending upon the ability of the seals and airlock fitted to the fermenting vessel). Allowing for a slight reduction in volume due to the lower temperature, where does the increase in pressure come from to increase Co2 in solution in the beer at the lower temperature??

Screwy


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## manticle (24/5/10)

My last question is - if I leave my finished brew in secondary for a week before cold conditioning, will the co2 blanket remain or not (normal plastic fermenter with glad wrap, glad wrap and lid or lid and airlock - I use all three depending on whatever is at hand).

Cheers


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## barls (24/5/10)

ok vessel contracts in relation to the drop in temp so the volume wont decrease a great deal but will stay in ratio to the vessel. the head pressure stays the same as its regulated by the airlock.
so we have a decrease in vessel size which could contribute to the increase in pressure then you also have the fact that beer has a high percentage of water and water being one of the few liquids that expands when it approaches freezing and boiling.
both of these factors can lead to a minor increase in pressure but its mainly the fact that as the liquid lowers in temp the solubility of co2 increases therefore needing less pressure to defuse into the liquid. 
wow i almost need a beer after that.
does this make sense.


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## Florian (24/5/10)

barls said:


> but you can see why i say its the current temp rather than the highest reached.
> say you have two beers. both reach say 22 in fermenting. at this point they have the same level of dissolved co2 you then rack both in to two separate but the same size secondry/ lagering vessel. the co2 is reduced at this point but still close.
> you take one and put it at 2 degrees and the other at room temp.
> you leave them for 3 weeks the one thats been in the fridge will have a higher dissolved co2 level than the one that hasnt.
> this needs to be taken in to account as with some styles it could mean the difference between hitting the right carb and completely overshooting it.


This is exactly how I see it as well, the one in the fridge has more C02 as it hasn't lost the C02 due to a temperature rise like the other one. But the question now is: What happens if you suddenly put the beer which has been outside in the fridge? If I understood you correctly, you say that it absorbs C02 and has eventually the same amount than the beer that has been in the fridge the whole time. Whereas I say, once it's lost it's lost and will not get back in to the beer just by itself (without pressure applied) just by lowering the temperature.

Just reading your example again, just to clarify: In your example are you transferring 3/4 through fermentation, just after the gross of C02 production has stopped, or after a few days, so there has been plenty of time for the C02 to escape at 22 degrees as no more is produced in the beer? second option would negate my statement completely. 

Anyway, just thinking this would be much easier to discuss this verbally...

Manticle, I don't believe that the C02 layer disappears just by itself. In my understanding it would stay indefinately, if it does not get blown away or 'manually removed' otherwise. As it is heavier than air, it will just sit in a bucket until someone pushes the bucket over or fills water to the brim and it therefore can flow out of the bucket.


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## manticle (24/5/10)

The reason I say that is because upon buying some glass demijohns for sour beers I was told that the co2 blanket would disappear completely after about 3 weeks (following ferment) and therefore I should reduce headspace in ageing vessels to 0. It certainly wouldn't hang around forever - it may be heavier than air but it pops out of the airlock ok, squeezes out past the glad wrap and certainly makes its way out of a beer glass and bottle if given the opportunity.


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## Hatchy (24/5/10)

I bulk prime everything with 140g of dex (give or take a couple of grams), I didn't know there was so much involved. I've never had bottle bombs or flat beer with 140g.


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## Screwtop (25/5/10)

barls said:


> ok vessel contracts in relation to the drop in temp so the volume wont decrease a great deal but will stay in ratio to the vessel. the head pressure stays the same as its regulated by the airlock.
> so we have a decrease in vessel size which could contribute to the increase in pressure then you also have the fact that beer has a high percentage of water and water being one of the few liquids that expands when it approaches freezing and boiling.
> both of these factors can lead to a minor increase in pressure but its mainly the fact that as the liquid lowers in temp the solubility of co2 increases therefore needing less pressure to defuse into the liquid.
> wow i almost need a beer after that.
> does this make sense.




No............. Because fermenting vessels can be plastic, metal or glass, and will not contract or expand at the same rate, or anywhere the same rate as the gas/liquid inside. Also from memory the solubility of Co2 in water is around 1.75 times "volume for volume" at 0 deg at one atmosphere of pressure and 1 atmosphere is equal to about 100 Kilopascals. I don't believe that we would ever have a situation where there was either enough pressure or a volume of 1:1 in the headspace of our fermentation vessels to achieve a significant variation in volumes of Co2 other than what existed prior to chilling of the wort. As we know, reducing temperature will not drive Co2 out of solution, therfore it should remain at the same level, but does not, the soluability increases, but only due to less volume of liquid at the lower temperature unless there is an increase in pressure at the gas/liquid interface. Unless driven off by agitation, a decrease in pressure or an increase in temperature soluability should remain stable. 

So soluability will change with a drop in the temperature of the beer but without a significant increase in pressure the amount of soluable Co2 in the beer will remain the same. Heating of the beer will be required to above the point where soluability will be affected and Co2 is driven out of solution again. 

My 2c

Screwy


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## Yeastie Beastie (25/5/10)

I have been using THIS CHART for a while now with no dramas at all.


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