Beersmith Carbonation Tool incorrect!

[Veldy]

So, I haven't bottled beer in more than a decade, but today, I decided too. I open up trusty beer smith and use the carbonation tool. Five gallons, just over 2.5 ounces of sugar (see attached). I proceed to bottle the entire batch. I run through my recipe and I spot that it says to use 5.03 ounces of sugar. What?!!! Of course, now I remember that 5 ounces is correct for 2.4 volumes and now I'm upset that my beer is going to be severely under carbonated.

 

[Gavin C]

WELCOME BACK TO HBT

You have bottling temp set to 40F

This temp should be the warmest temp the beer got to after fermentation was complete. That will be warmer that 40F. (Probably 70+F). Correct that error in your data and beer smith will tell you a different weight of sugar.

G.I.G.O

 

[kh54s10]

Gavin is right and that gives a result of 4.2 ounces. Seems right to me. I use the calculator on Northern Brewer's website.

 

[Veldy]

Wasn't obvious to me...that temp only makes sense as serving temp; I don't think anybody bottle or keg conditions at 40 degrees as all but the heartiest lager yeast would be completely dormant. At the very least that is a poor default value in Beersmith in my opinion.

 

[Veldy]

I posted about it over at Beersmith forums. Thanks for the help guys!

 

[Oginme]

Wasn't obvious to me...that temp only makes sense as serving temp; I don't think anybody bottle or keg conditions at 40 degrees as all but the heartiest lager yeast would be completely dormant. At the very least that is a poor default value in Beersmith in my opinion.

It makes sense when you take into consideration the amount of CO2 already dissolved in the beer when you are bottling. AT 40F, there is already a good amount of dissolved CO2 (somewhere around 1.3 to 1.4 volumes if I remember correctly), so your sugar is making up the difference between the already dissolved CO2 and the desired outcome (1.35 to 2.4 volumes).

 

[broadbill]

It makes sense when you take into consideration the amount of CO2 already dissolved in the beer when you are bottling. AT 40F, there is already a good amount of dissolved CO2 (somewhere around 1.3 to 1.4 volumes if I remember correctly), so your sugar is making up the difference between the already dissolved CO2 and the desired outcome (1.35 to 2.4 volumes).

^^^^This; all of the other explanations are either confusing or misleading.

 

[Gavin C]

The current temperature of the beer when bottling should be ignored.

The temperature of concern is the warmest the beer was after production of CO2 in the liquid stopped. (ie. after fermentation is complete)

The carbonation tool in BS is geared toward all methods of carbonation.

The residual CO2 in the beer/cider is only important if bottling.

 

[broadbill]

The current temperature of the beer when bottling should be ignored.

The temperature of concern is the warmest the beer was after production of CO2 in the liquid stopped. (ie. after fermentation is complete)

The carbonation tool in BS is geared toward all methods of carbonation.

The residual CO2 in the beer/cider is only important if bottling.

cut/paste from the BeerSmith 2 help file: LINK
Using the Carbonation Tool

o Select the Carbonation Tool from the Tools menu or ribbon.
o Enter the target number of volumes of CO2 which will determine your carbonation level. Most beers require between 2.0 and 3.0 volumes, though a few styles run lower or higher than that range.
o If bottling, enter the temperature of the beer when it is bottled(often room temperature). If kegging, enter the intended storage temperature for the keg (typically the temperature of the refrigerator you will be storing the keg in).
o Enter the volume of the finished beer
o If kegging, the tool will display your target carbonation pressure for forced carbonation. As an alternative you can also consider naturally carbonating your keg with the amount of corn sugar shown, though natural carbonation in kegs is rarely used today.
o For bottling, the corn sugar weight or alternatively dry malt extract weight to use for bottling the beer is displayed.

In no situation would you use a "historical" temperature reading of the beer during fermentation. I can't even understand the rationale for this, or how you would standardize it (e.g. how would i know the exact moment when CO2 production stopped?). Very confusing.

 

[Gavin C]

cut/paste from the BeerSmith 2..... [sic]Bad instructions.... I think it's [sic] very confusing.

Those instructions are inaccurate. The temperature at bottling may be the warmest the beer has gotten to but it may not be, particularly if you crash cool as the OP seems to have done (albeit only to 40F).

Bottling 101.
In every situaton one should use the warmest temp the beer got to after completion of fermentation and production of CO2 in the beer has stopped.

Once that has happened the amount of CO2 in the beer is governed solely by the maximal temperature reached. Know that temperature and you know how much CO2 remains and how much needs to be added.

Henry's Law is the basic physical law governing this not some instructions in a piece of software.

Kegging 101.
Where the current, or more correctly the storage temperature is of importance is of course with force carbonating the beer. Partial pressure of the CO2 in the headspace and temperature of the beer determine the volumes of CO2 absorbed.

 

[Veldy]

I agree that the amount of CO2 after fermentation and before bottling is inversely related to the maximum temp of the beer during this interval. Once bottled, the temperature only matters to keep the yeast alive or serve).

I still maintain that temp is poorly described in the carbonation tool (and it means something totally different for bottle conditioning than it does for force carbonation in a keg).

That tool might be better suited using radio buttons to switch between bottle conditioning and force carbonation.

The above could solve the unintuitive problem I have noticed.

 

[broadbill]

dup

 

[broadbill]

Those instructions are inaccurate. The temperature at bottling may be the warmest the beer has gotten to but it may not be, particularly if you crash cool as the OP seems to have done (albeit only to 40F).

Bottling 101.
In every situaton one should use the warmest temp the beer got to after completion of fermentation and production of CO2 in the beer has stopped.

Once that has happened the amount of CO2 in the beer is governed solely by the maximal temperature reached. Know that temperature and you know how much CO2 remains and how much needs to be added.

Henry's Law is the basic physical law governing this not some instructions in a piece of software.

Kegging 101.
Where the current, or more correctly the storage temperature is of importance is of course with force carbonating the beer. Partial pressure of the CO2 in the headspace and temperature of the beer determine the volumes of CO2 absorbed.

But Henry's Law (or the Constant) also changes when the temperature of the system changes, which is what we are discussing here.

Henry's Law states that the solubility of a gas increases with decreasing temperature (or least it does in the case of CO2). If I understand what you are saying, you are implying that a beer will not have more CO2 dissolved in it if is cooled from 70 to 40. Are you saying that the beer would not hold more CO2 at 40 because it has already been at 70 and lost it? Wouldn't it equilibrate at the lower temp with atmospheric CO2?

 

[Oginme]

Those instructions are inaccurate. The temperature at bottling may be the warmest the beer has gotten to but it may not be, particularly if you crash cool as the OP seems to have done (albeit only to 40F).

Bottling 101.
In every situaton one should use the warmest temp the beer got to after completion of fermentation and production of CO2 in the beer has stopped.

Once that has happened the amount of CO2 in the beer is governed solely by the maximal temperature reached. Know that temperature and you know how much CO2 remains and how much needs to be added.

Henry's Law is the basic physical law governing this not some instructions in a piece of software.


Since the OP is talking bottling, we can all skip the kegging comments to address his concerns directly.

Henry's Law: At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.


Even if the wort had completed fermenting at a higher temperature, when chilled and held at a lower temperature, the CO2 dissolved in the wort will come into equilibrium with the partial pressure of the atmosphere above it (nearly 100% CO2 for all practical purposes) since the head space in the carboy has been filled with the CO2 from fermentation pushing most of the rest of the gases out. [given that any starting O2 has most likely been used by the yeast and N2 is not soluble in wort]

If the amount of a gas dissolved in a fluid, such as wort, were dictated by the amount contained at the highest temperature it reached after fermentation ceased, then we could all breathe a sigh of relief, since the prospect of oxidation would now cease to become a concern.

 

[Veldy]

I agree 100% as to what it means. Now, I would love it if the tool were made more intuitive so one didn't figure this out the wrong way. A simple solution is to redesign the tool using a radio button to choose which mode (bottle/keg condition or force carbonation) and adjust the controls (and descriptions) and calculations accordingly. That would be obvious to any user.

 

[Gavin C]

Are you saying that the beer would not hold more CO2 at 40 because it has already been at 70 and lost it?

Yes.

Wouldn't it equilibrate at the lower temp with atmospheric CO2?

It does equilibrate. CO2 unfortunately is only ~0.04% of our atmosphere.

For all intents and purposes there is zero gain of CO2 as a result of cooling the beer. Oxygen absorption is the greater concern at this time but that's a different thread.

 

[Oginme]

Yes.



It does equilibrate. CO2 unfortunately is only ~0.04% of our atmosphere.

For all intents and purposes there is zero gain of CO2 as a result of cooling the beer. Oxygen absorption is the greater concern at this time but that's a different thread.

While that is true, in the headspace above the fermented beer, the concentration of CO2 is much higher due to the production of CO2 diluting and pushing out the initial air volume of the carboy.

 

[Yooper]

While that is true, in the headspace above the fermented beer, the concentration of CO2 is much higher due to the production of CO2 diluting and pushing out the initial air volume of the carboy.

No, it's still subject to the laws of physics. The air in the carboy above the beer is just that- air.

While it's true that active fermentation does produce c02 that will be in the headspace, the laws of physics still apply and gasses come through the water in the airlock, through the sides of the bung, etc, and that is why headspace is a concern later on and why winemakers are sure to always top up once fermentation slows/stops. Gasses will seek equilibrium, and once fermentation slows/stops, the production of c02 also slows/stops and the "c02 blanket" that some refer to is not actually a real thing. If it was, we'd all die in our sleep.

 

[Veldy]

The CO2 blanket is a real thing. CO2 is heavier than air and sits on top of the fermented beer. Only drafting it away by opening the carboy to open air and agitating it will drive it off.

We don't die in our sleep because our homes are not sealed that well...if they were, we'd run out of oxygen. As it stands, air is exchanged at such a rate that oxygen gets in and excess CO2 gets out. This is both by design (to avoid mold and disease growth) and a matter of practical life...we poke holes through moisture barrier with nails and for wiring.

 

[Yooper]

The CO2 blanket is a real thing. CO2 is heavier than air and sits on top of the fermented beer. Only drafting it away by opening the carboy to open air and agitating it will drive it off.

We don't die in our sleep because our homes are not sealed that well...if they were, we'd run out of oxygen. As it stands, air is exchanged at such a rate that oxygen gets in and excess CO2 gets out. This is both by design (to avoid mold and disease growth) and a matter of practical life...we poke holes through moisture barrier with nails and for wiring.

Sorry, but that just isn't so. Gasses mix- that is what gasses do. During active fermentation, there is c02 being produced and some is in the carboy while some goes out the airlock- but after fermentation slows, the laws of physics still apply and the air in the headspace will not be so heavy with c02 following. It dissipates and gasses mix.

 

[Oginme]

Let's examine his hypothesis of the layer above the wort as being just air:

We can start by stipulating that the carboy is a reasonably closed system with air only able to come in or out through the air lock on the top of the carboy to maintain atmospheric pressure on the inside of the carboy.

I will take my system as an example (also because it makes the math easier to follow): I ferment 10 liter batches in a carboy which has a total volume of 11.3 liters. This gives a head space of 1.3 liters of air when closed.

So we have an air pocket which let's say has no CO2 to start with.

Fermentation of a 1.040 gravity wort at 20C with 75% attentuation will give an approximate release of 150 liters of CO2. This means that the air displacement inside the carboy is [150/1.3] about 115 times.

For s&gs, we assume that every full displacement is a halving of the original air concentration. This means that the first 1.3 liters creates an an air concentration of 50% CO2 and 50% original air. We have 115x halving of the original air concentration during active fermentation. The resultant concentration of the original air volume is now at 2.4 x 10^-35, with the balance being CO2.

Now, as Yooper correctly pointed out, the airlock is not perfect and concentrations across a membrane (we will simplify the airlock as being a semi-permeable membrane for this exercise) is in relation to the concentration difference of the various gasses in our system. During fermentation, the production of CO2 from the wort/beer forces all of the air movement out of the carboy, so there is little influx of air.

From the Better Beer produced study, the permeability of a 3-piece airlock is approximately 1.6 ml/day of O2 in a quiescent system. Oxygen is 21% of total air volume, so the movement of total air is 7.6 ml per day. Taking the worst case scenario, we will assume no mixing of the air (unlike when we displaced the original air volume). This means that to return to original air concentrations, the carboy would need to sit for [1.3 liters/7.6 ml] approximately 171 days post fermentation.

Two weeks of sitting beyond the finish of fermentation would give us an inflow of (7.6 x 14) = 106 ml of air or about 8.2% CO2 displacement (again, assuming no mixing). So our air concentrations will be something of the order of 22 ml of O2, 82 ml of N2, and 1196 ml of CO2. Compared to the standard atmospheric concentration of .04% (0.5 ml of the 1300 ml of head space we began with), we are roughly about 2292 times richer in CO2 with a much higher partial pressure than atmospheric attributed to CO2.

As to the 'die in our sleep' analogy, if you sleep with a low permeability bag covering your head, then yes, you will die in your sleep as the influx of air across the barrier is lower than your bodily exchange of CO2 for O2 within the mostly confined environment. However, most of us sleep in a larger room with a higher permeability than a bag. The act of breathing creates air movement which exchanges the CO2 richer air you exhale with the air in the room, thus allowing us to all sleep without fear of Oxygen depletion.

 

[Yooper]

This means that to return to original air concentrations, the carboy would need to sit for [1.3 liters/7.6 ml] approximately 171 days post fermentation.

unless.................you ever, ever, opened the carboy to take a reading. Or used a bucket which doesn't seal perfectly, or the bung wasn't completely sealed, etc. Most people take at least one reading and don't let a carboy sit without a single move, temperature variation, or without opening. Even temperature variations make a difference in the dissolution of gasses (c02), as that is what we are talking about here.

 

[Veldy]

Sorry, but that just isn't so. Gasses mix- that is what gasses do. During active fermentation, there is c02 being produced and some is in the carboy while some goes out the airlock- but after fermentation slows, the laws of physics still apply and the air in the headspace will not be so heavy with c02 following. It dissipates and gasses mix.

CO2 is heavier than air and emitted by the surface of the fermenting beer, pushing air upward from the bottom. Further, it is a laminar flow, not turbulent. In hours of fermentation, all air is pushed out the airlock leaving only CO2 in the headspace. Laminar flow means mixing occurs very slowly...much more slowly than the rate air is pushed out of the airlock. Unless you open the fermenter or cool the beer to pull air back through the airlock, there is absolutely no air in the headspace after fermentation.

Besides, the only thing in air you don't want in your beer is oxygen, and if not pushed out of the airlock, it would have been consumed by yeast during aerobic reproduction. There is simply no chance there is any left in the headspace after fermentation in a carboy with an airlock.

 

[Veldy]

unless.................you ever, ever, opened the carboy to take a reading. Or used a bucket which doesn't seal perfectly, or the bung wasn't completely sealed, etc. Most people take at least one reading and don't let a carboy sit without a single move, temperature variation, or without opening. Even temperature variations make a difference in the dissolution of gasses (c02), as that is what we are talking about here.

Mixing isn't instantaneous. In fact without agitation, the introduced air will stratify and sit on top....eventually mixing in after a long duration...so don't pick up and agitate your beer if you introduced air into the head space. Taking a gravity reading may introduce a small amount of air, but it also may agitate enough CO2 out of the beer when doing so and the air will be pushed right back out.

Use common sense, don't over think it. If your beer turns out, then you clearly didn't have a noticeable amount of oxygen in your carboy head space after all. For that reason, my experience says there is no air in the headspace of my carboys...because my beer isn't stale.

 

[Yooper]

Mixing isn't instantaneous. In fact without agitation, the introduced air will stratify and sit on top....eventually mixing in after a long duration...so don't pick up and agitate your beer if you introduced air into the head space. Taking a gravity reading may introduce a small amount of air, but it also may agitate enough CO2 out of the beer when doing so and the air will be pushed right back out.

Use common sense, don't over think it. If your beer turns out, then you clearly didn't have a noticeable amount of oxygen in your carboy head space after all. For that reason, my experience says there is no air in the headspace of my carboys...because my beer isn't stale.

It's great that "there is no air in the headspace of my carboys.......because my beer isn't stale", and that really is the important thing. I'm not here to argue with success, and if your beer is great and the way you like it, it is definitely a success!

We've taken this WAY off topic, but the science part still stands. Just as science is the reason for the error in the priming calculation, science is still behind the reason gasses don't stratify. If anybody cares about the science part of why there IS air in a carboy, this is a good (but also contentious!) read that is science based: https://www.homebrewtalk.com/showthread.php?t=431015&highlight=stratification

 

[Veldy]

If gas doesn't stratify, then why does carbon monoxide poisoning kill people more easily in areas where it rises too rather than everybody equally? Before you say that it's hotter...think about it

 

[ba-brewer]

Big carboy model?

http://news.bbc.co.uk/onthisday/hi/dates/stories/august/21/newsid_3380000/3380803.stm

 

[pricelessbrewing]

Physicist here. @Oginme is correct for the scenario of a perfectly closed system, up until the point of opening that fermentation vessel. After that point it's more or less back to atmosphere (for buckets especially).


Back on topic: You use the temp reached by the beer once fermentation stopped. Usually around room temp. Not the cold crashed or stored temp.

Brad smith instructions are rather poor in a lot of cases, his terminology is not correct pretty often (boiling doesn't sterilize!!!), and he uses some out of date informatioe. I don't really consider him a good source of info.