Why does carbing take so long? Explain...

[Homercidal]

I'm siding with Bobby on this one. In fact, I was going to post that along with my other post, but after getting started found it hard to get into words. I'm less medicated now.

I think the yeast, beer, and everything else is at an equal pressure, including the gas produced. So it makes sense that anything coming out of the walls of the yeast cells is in solution. It might even be this way for beer that is at normal pressure, and that Bubbles, or CO2 GAS, is only formed when several molecules of CO2 come together, when they then float to the surface of the fermenter as a gas (Having enough mass to create a large enough bubble to see and actually rise to the surface.)

I wonder if anyone makes a 1-wire pressure sensor that could be fitted into a bottle cap or some other vessel suitable for a small amount of pressure.

 

[unionrdr]

Seems to me I saw an invention like that on youtube last month...

 

[NordeastBrewer77]

I'm less medicated now.

I hope that you've found a solution to that problem.

Seems to me I saw an invention like that on youtube last month...

I remember something like that too. Can't remember who's video it was, but my guess is that Bobby's seen it too.
I don't really have anything to contribute other than I've always been under the impression that co2 does go into the headspace first (talking in ~room temp liquids) and then will dissolve into solution as temps are lowered. But, I've always been under this impression because of what I've read. What I've seen is that bottle or keg, chilling is what gets the perception of carbonation in the beer. I'd be really interested to see at what rates and temps the co2 actually dissolves into the liquid.

 

[unionrdr]

It seems to me from observation that carbonation absorbtion is linked to the temp of the fridge & the gravity of the beer. Lighter gravity can absorb co2 more quickly than a high gravity example. A pale ale may have great carbonation at one week fridge time. But my dark whiskely ale took 2 weeks fridge time to get decent head & carbonation.

 

[AnOldUR]

From BYO:

Natural conditioning relies on residual yeast suspended in the beer that didn’t settle out during fermentation. The yeast consumes the priming sugar and releases carbon dioxide. Because the bottle or keg is capped, the carbon dioxide is not able to escape. Over time the trapped carbon dioxide dissolves into the beer, naturally carbonating it. Typically the carbonation process requires two to three weeks to complete.

Don't know if this is right or wrong. Just putting it out there.

 

[Bobby_M]

Normal dudes like you and I write the articles for BYO so they can easily repeat mistaken understandings in print. Think about this on the microscopic scale. Let's go back to the definition of carbonation; "Co2 molecules dissolved in an aqueous solution". Some CO2 reacts to H2O and becomes carbonic acid, but most of it just swims as single CO2 molecules. As yeast are releasing CO2, it's one molecule at a time. A single CO2 molecule in liquid is already considered dissolved. Because the source of CO2 in bottle conditioning is in the liquid already the liquid will always have the higher concentration of CO2 compared to the headspace until no more CO2 is being produced. At that point equilibrium is reached and the concentration will be equal.

I think people relate to the idea of the headspace being pressurized because of intermingling the concept of bottle conditioning with keg force carbing. That original experiment with the pressure gauge on the bottle was easy to mess up because of confirmation bias. The conclusion was inline with the preconception. Other than the temp impact that I was mostly concerned about, another reason that pressure could spike and drop later is deformation of the lid creating a small leak. Once the pressure dropped, the lid seal would be become effective again and level off. I'm not saying I know this happened, but it's another posibility.

 

[helibrewer]

Normal dudes like you and I write the articles for BYO so they can easily repeat mistaken understandings in print. Think about this on the microscopic scale. Let's go back to the definition of carbonation; "Co2 molecules dissolved in an aqueous solution". Some CO2 reacts to H2O and becomes carbonic acid, but most of it just swims as single CO2 molecules. As yeast are releasing CO2, it's one molecule at a time. A single CO2 molecule in liquid is already considered dissolved. Because the source of CO2 in bottle conditioning is in the liquid already the liquid will always have the higher concentration of CO2 compared to the headspace until no more CO2 is being produced. At that point equilibrium is reached and the concentration will be equal.

I think people relate to the idea of the headspace being pressurized because of intermingling the concept of bottle conditioning with keg force carbing. That original experiment with the pressure gauge on the bottle was easy to mess up because of confirmation bias. The conclusion was inline with the preconception. Other than the temp impact that I was mostly concerned about, another reason that pressure could spike and drop later is deformation of the lid creating a small leak. Once the pressure dropped, the lid seal would be become effective again and level off. I'm not saying I know this happened, but it's another posibility.

I'm totally onboard with this and is how I consider this happens. Boyle's Law, Charle's Law and all that good stuff...

 

[Hackwood]

I usually try a beer every 7 days until I call it good to go.

That's it for me as well. MOST that I have done have been good after 7 days. This latest extract Summer Ale is taking much much longer though(I used regular table sugar as I was out of corn sugar). Weird thing was, to me, is that I brewed my all-grain Summer Ale the very next day and bottled them the same day and primed exactly the same and the all-grain was good at the 7 day mark.

Extract has been sitting for a few more weeks and now is much better. Both are still bottle aging but both are now good/awesome and ready at any time for the fridge. Guess I'll get on that after today's brew gets in the fermenters.

 

[AnOldUR]

I'm totally onboard with this and is how I consider this happens. Boyle's Law, Charle's Law and all that good stuff...

So, Bolyle's law and Charle's law prove that the C02 from fermentation is absorbed into the wort at the same rate as it's produced? Knew that someone else must have done this work. I'm a blue collar guy and won't pretent to know or understand the science behind it, but it's already a proven fact, so there's no need to do this experiment. Thanks for the heads-up. Saved me some time.

 

[Bobby_M]

No, I think it's worth doing given how people will relate to watching it unfold as performed by a fellow forum member.

 

[unionrdr]

Yup. We've proven popular theories wrong on here from our own experiments,myself included. It can def be a good thing that advances our understanding of the brewing process.

 

[billl]

"Normal dudes like you and I write the articles for BYO so they can easily repeat mistaken understandings in print. Think about this on the microscopic scale. Let's go back to the definition of carbonation; "Co2 molecules dissolved in an aqueous solution". Some CO2 reacts to H2O and becomes carbonic acid, but most of it just swims as single CO2 molecules. As yeast are releasing CO2, it's one molecule at a time. A single CO2 molecule in liquid is already considered dissolved. Because the source of CO2 in bottle conditioning is in the liquid already the liquid will always have the higher concentration of CO2 compared to the headspace until no more CO2 is being produced. At that point equilibrium is reached and the concentration will be equal."

While I understand where you are going with this, the rolling bubbles in my fermenter are very strong evidence that not all of the CO2 is staying as individual molecules in solution from the get-go. They are bumping together, congregating, and rising. Lots of gas is obviously reaching the surface as bubbles and not just diffusing as individual molecules. If it were a pressurized environment like a bottle, that CO2 would slowly be reabsorbed into solution until it reached equilibrium.

I think it is fair to say that both processes (and probably a lot more) are happening simultaneously.

 

[Bobby_M]

While I understand where you are going with this, the rolling bubbles in my fermenter are very strong evidence that not all of the CO2 is staying as individual molecules in solution from the get-go. They are bumping together, congregating, and rising. Lots of gas is obviously reaching the surface as bubbles and not just diffusing as individual molecules. If it were a pressurized environment like a bottle, that CO2 would slowly be reabsorbed into solution until it reached equilibrium.

I think it is fair to say that both processes (and probably a lot more) are happening simultaneously.

You're not appreciating the vast difference between an open and closed system. Bubbles form in the fermenter because it's an open system. The headspace has CO2 gas at atmospheric pressure and of course anything above that level in the fermenting wort is going to form bubbles. In a closed system, there is no bubble formation.

It's intuitive to suspect as you do, because of what you observe in an open fermentation but it's incorrect to apply the same understanding to bottle conditioning.

This is why anoldUR should still do the experiment, as should anyone else with the means to graph pressure and temp.

 

[BuddyWeiser]

The CO2 is produced in the beer. When the headspace has lower pressure than the beer, CO2 will move out of the beer into the headspace until pressure regains an equilibrium between the two. The beer gets the CO2 first, and only shares it with the headspace when it has to. This happens constantly and in very small amounts until the yeast has burped out all of the CO2 that it can.

As you drop the temp, the beer can absorb more CO2, creating a vacuum (because the temp change does not affect gas as drastically as liquid). A little bit of CO2 will slowly move from the headspace into the beer as the temperature drops until a pressure equilibrium and constant temperature are reached. However, most of the CO2 (maybe 2/3rds or more) is/was already in the beer from the moment the yeast produced it/before the temp was dropped.

The top and bottom of the bottle pretty much pressurize together as a sealed unit, but the CO2 starts in the beer.

Back to the op, I still think bottle carb'ing takes longer due largely to a lack of oxygen/O2. This lack of O2 prevents the yeast from reproducing, so the yeast that get poured into the bottles must eat up the priming sugar by themselves. There is also the added issue of alchol present that makes it even slower because less yeast can survive/continue eating sugar.

Imagine how long primary fermentation could take if you didn't aerate the wort, and had only the yeast from your starter or yeast pack to do the job. They might all get old, tired, and die off before fermentation is complete.

You could test my hypothesis by adding dry yeast to your bottles before sealing them up.

 

[Bobby_M]

As you drop the temp, the beer can absorb more CO2, creating a vacuum (because the temp change does not affect gas as drastically as liquid). A little bit of CO2 will slowly move from the headspace into the beer as the temperature drops until a pressure equilibrium and constant temperature are reached. However, most of the CO2 (maybe 2/3rds or more) is/was already in the beer from the moment the yeast produced it/before the temp was dropped.

I think it's actually the other way around. Though CO2 is more soluable in liquids as the temp drops, the pressure of the gaseous space is reduced at the same time (subject to slight temp variations).

If you have 3 volumes of CO2 in a sealed bottle at the moment the yeast crap out, it is likely at equilibrium between the beer and headspace already. This assumption is based on the fact that new CO2 was barely being added towards the end and the equilibrium had plenty of time to be reached.

Anyway, back to the 3 volumes. It doesn't matter how much the temperature or pressure changes at this point. Raise the temperature and the pressure increases. Lower the temp and pressure decreased but the total number CO2 molecules doesn't change.

Assuming the 3 volumes were achieved at 70F, the pressure of the headspace is now 36.8psi. Put the bottle in the fridge and it's likely that the headspace will be a little colder the the beer and that delta will remain until it's all the same temp as the fridge. Let's figure out what happens when the headspace falls to 60F (and we'll take a WAG that the beer is still 68F). The pressure in the headspace falls to 30psi due to Gay-Lussac's law and I agree that between the time you start chilling and when the beer is fridge temp, there may be a slight differential in CO2 concentration.

It would be in the other direction if you submerged just the lower half of the bottle into icewater. The beer is a little colder than the headspace for a while, and the concentration can move to the beer side slightly until the temps equalize.

This is all really small though and it doesn't support the idea that you have to let CO2 be reabsorbed back into the beer after all the yeast burps it into the headspace.

 

[BuddyWeiser]

It makes sense the headspace would get cold quicker than the beer, and because of this I can see why CO2 would go from the beer into the headspace right at first when the temp starts dropping. Once the headspace is as cold as it's gonna get, the beer would cool down next, reabsorbing the CO2 that was lost when the headspace cooled.

I just think the beer would reabsorb even more CO2 than it had in it before the bottle began cooling down. The solubility of the CO2 should increase as the temp drops, causing an increase in carbonation.

 

[Bobby_M]

But again, it's a fully closed system. If a bottle has 10 volumes at 100F, it has 10 volumes at 33F. Where does the "more co2" come from? The only real difference is what temp the beer is when you open the system again. If the beer is warm, the CO2 practically jumps out of solution at ambient pressure. If it's ice cold, it comes out much slower.

 

[BuddyWeiser]

Maybe the increase in CO2 solubility at lower temps allows gravity to pull more CO2 from the headspace into the beer, creating a lower pressure in the headspace and higher pressure in the beer.

 

[zeg]

(Wow, this turned out a lot longer than I'd planned...)

Buddyweiser is correct, but it doesn't make a significant difference in carbonation. As the temperature drops, the solubility of CO2 increases. This pulls more CO2 into solution (in time). The pressure in the headspace drops---partly because of the temperature drop, but mostly because of the solubility increase.

I played around with a solubility calculator I found here (http://www.geo.unibe.ch/diamond/publications.php?PID=40289553, search down for CO2 in the publications list) and the ideal gas law to get a feel for this. For simplicity, I assumed that beer is the same as water (so the following may only apply to Coors Light). The bottle was assumed to have 30 mL head space and 355 mL liquid. (That's perhaps an overestimate of the head space, but it doesn't make a real difference to this level of precision.) From comparison with this carbonation chart (which I found through Google and don't trust for any other reason than someone put it up on the internet), my calculations are a bit off in the absolute numbers, but I think they are correct in the relative sense.

355 mL of beer with 2 volumes CO2 has 1.40 g of CO2 dissolved (using the definition of a "volume" I found here). This requires a solubility of 1.4g CO2 / 0.355 kg H2O = 3.94 g/kg. According to the calculator, this occurs at 1.97 atmospheres of CO2 in the head space. Using the ideal gas law, that's 0.11 g of CO2 gas. In total, then, we have 1.51 g of CO2 split between solution and gas.

Now let's crash this to 1°C and see what happens. The bottle is a closed system, so we still have 1.51 g total, but presumably the proportion in solution will change. By assuming that m_gas + m_liquid = 1.51 g and applying the ideal gas law, you can find that equilibrium will occur when P=(2.60e6)-(6.12e5)*S(T=1°C, P), where P is the CO2 pressure in the head space and S(T,P) is the solubility at the given temperature and pressure.

Because I have nothing better to do, I played with the calculator until I found a consistent solution. This occurs at about 1.23 atmospheres. At this point, the solubility has increased a small amount to 4.05 g/kg, so there is now 1.44 g of CO2 in solution. This leaves 0.07 g of CO2 as gas in the headspace.

For comparison, had we simply computed the pressure in the headspace using PV=nRT, we'd have found 1.84 atmospheres. So the rather small increase in solubility really seems to dominate the pressure change---there's very little CO2 in the head space, and a lot of beer to absorb it.

Finally, the change in volumes is small: 2 volumes was 1.4 g dissolved, so we've only increased to 2.06 or so. I don't think many homebrewers carb to that level of precision. So Bobby_M is also right. :fro:

 

[AnOldUR]

The bottle was assumed to have 30 mL head space and 355 mL liquid.. . . Finally, the change in volumes is small: 2 volumes was 1.4 g dissolved, so we've only increased to 2.06 or so. I don't think many homebrewers carb to that level of precision. So Bobby_M is also right.

And since the head space in an average 12 ounce bottle is more like 10-15 ml the difference is even less. Serving temperature or room temperature, the volumes of Co2 in a bottle of beer are the same for practical purposes.

Although it makes sense, I'm still having trouble wrapping my brain around the CO2 formed during carbonation going right into solution.

 

[zeg]

And since the head space in an average 12 ounce bottle is more like 10-15 ml the difference is even less. Serving temperature or room temperature, the volumes of Co2 in a bottle of beer are the same for practical purposes.

Although it makes sense, I'm still having trouble wrapping my brain around the CO2 formed during carbonation going right into solution, but Buddyweiser's statements are hard to take seriously.

Yeah, like I said, I didn't bother checking what the headspace volume actually is. In any case, even if 100% of the gas dropped into solution, you'd have no appreciable difference in carbonation unless you left the bottle a couple ounces short.

I don't have any idea whether the idea that the CO2 is instantly insolution is correct. I do think you can get some idea of the timescales involved in absorption by looking at the reverse process: watching CO2 escape from solution after you've poured a beer and the CO2 partial pressure is ~0. Since that's about an hour (order of magnitude), the dissolving process is probably not grossly different (though there are complications, and it certainly could be). So I'm not sure how to connect that with the standard claim that it takes ~3 days of refrigeration for a bottle to be ready (or ~5 days for force carbing a keg), as both of those are ~100 times longer than the go-flat time. Either something else is going on, or the rate is much slower for absorption for some reason.

 

[AnOldUR]

This is why anoldUR should still do the experiment, as should anyone else with the means to graph pressure and temp.

Why not? Put something together this morning before work. Didn't have any beer ready to bottle, so threw some Munton carb tabs in water with yeast nutrient and added a little dry yeast. I’m not looking to draw any serious conclusions from this. Just want to make sure the system is sealed and will hold pressure. If this works out I’ll do it with some proper controls in place.

I used 20 of the little Munton tabs in 32 ounces of water and about a ¼ teaspoon of US-04 yeast.

Edit-1:
So far, so good. Here it is at 5 psi after around 6 hours at 70 degrees.

Edit-2:
This morning, after 20 hours, it's at 13 psi. The temperature dropped about a degree because of the cooler night.

Final Edit:
Moved my experiment to here, but the bottom line is that there was no spike and drop in pressure. This has me believe that there is no build up of CO2 in the headspace prior to absorbsion when naturally carbonating beer.

.

 

[feinbera]

...or the rate is much slower for absorption for some reason.

That reason is that you're dramatically changing the environment the beer is in. The amount of pressure in the air the beer is touching affects the amount of gasses the beer can absorb -- higher-pressure air forces more of itself into the fluid. The headspace in your bottles is at a much higher PSI than Earth's atomsphere -- this high-pressure air escaping is why the bottles hiss when you open them, even before the beer starts foaming. However, once the pressure is no longer "holding the absorbed gas in," it's free to escape the beer, and will do so much faster than it was forced in.

Think about blowing up a balloon -- the first few breaths are easy, but it gets harder and harder, and it can take a minute to really get it good and full -- but, if you accidentally let it go before you tie it, it will be empty again in a couple seconds, even with the air escaping from the same hole it entered through. The pressurized headspace takes the role of your lungs, forcing air in, and the beer itself takes the role of the rubber walls of the balloon, readily allowing more CO2 in initially, resisting more strongly the more CO2 is already in, and expelling the CO2 once the pressure is released.

 

[res291que]

That reason is that you're dramatically changing the environment the beer is in. The amount of pressure in the air the beer is touching affects the amount of gasses the beer can absorb -- higher-pressure air forces more of itself into the fluid. The headspace in your bottles is at a much higher PSI than Earth's atomsphere -- this high-pressure air escaping is why the bottles hiss when you open them, even before the beer starts foaming. However, once the pressure is no longer "holding the absorbed gas in," it's free to escape the beer, and will do so much faster than it was forced in.

Think about blowing up a balloon -- the first few breaths are easy, but it gets harder and harder, and it can take a minute to really get it good and full -- but, if you accidentally let it go before you tie it, it will be empty again in a couple seconds, even with the air escaping from the same hole it entered through. The pressurized headspace takes the role of your lungs, forcing air in, and the beer itself takes the role of the rubber walls of the balloon, readily allowing more CO2 in initially, resisting more strongly the more CO2 is already in, and expelling the CO2 once the pressure is released.

That makes a lot of since.

 

[zeg]

That reason is that you're dramatically changing the environment the beer is in. The amount of pressure in the air the beer is touching affects the amount of gasses the beer can absorb -- higher-pressure air forces more of itself into the fluid. The headspace in your bottles is at a much higher PSI than Earth's atomsphere -- this high-pressure air escaping is why the bottles hiss when you open them, even before the beer starts foaming. However, once the pressure is no longer "holding the absorbed gas in," it's free to escape the beer, and will do so much faster than it was forced in.

Think about blowing up a balloon -- the first few breaths are easy, but it gets harder and harder, and it can take a minute to really get it good and full -- but, if you accidentally let it go before you tie it, it will be empty again in a couple seconds, even with the air escaping from the same hole it entered through. The pressurized headspace takes the role of your lungs, forcing air in, and the beer itself takes the role of the rubber walls of the balloon, readily allowing more CO2 in initially, resisting more strongly the more CO2 is already in, and expelling the CO2 once the pressure is released.

Yes, it's pressure that puts the CO2 in solution. But I don't think this is a detailed enough description to draw much of a conclusion about the relative rates. The headspace being high pressure should *increase* the rate of absorption. The atmosphere being low pressure should *increase* the rate of escape. Those both work in the same direction, so you need to be careful to estimate the actual rates.

Suppose you are force carbing, and starting with a completely CO2-depleted beer. You put some high number of PSI on it. Initially, there's very little dissolved CO2, so the rate of absorption is high. As it reaches saturation, the rate slows.

Now you wait until everything is equilibrated and you open the bottle. The pressure outside is now low, so the CO2 escapes quickly at first because there is a high concentration in the beer. As that concentration drops, the escape rate will again decrease because the dissolved CO2 produces less "pressure" to escape.

So it's not obviously asymmetric with the absorption. The change when you applied the pressure to force carb is every bit as sudden as the change when you open the bottle. A more detailed look at the processes is needed.

I think the bubbles may be the difference: most of my reasoning is based, at least roughly, on this being a smooth, diffusive process. On escape, though, clearly there is something else going on where you get bubbles forming and escaping non-diffusively. I guess this may result from the solubility itself being a function of pressure, in which case you get a step drop in solubility and then have a supersaturated solution, which is unstable.

 

[Bobby_M]

Yeah, like I said, I didn't bother checking what the headspace volume actually is. In any case, even if 100% of the gas dropped into solution, you'd have no appreciable difference in carbonation unless you left the bottle a couple ounces short.

I don't have any idea whether the idea that the CO2 is instantly insolution is correct. I do think you can get some idea of the timescales involved in absorption by looking at the reverse process: watching CO2 escape from solution after you've poured a beer and the CO2 partial pressure is ~0. Since that's about an hour (order of magnitude), the dissolving process is probably not grossly different (though there are complications, and it certainly could be). So I'm not sure how to connect that with the standard claim that it takes ~3 days of refrigeration for a bottle to be ready (or ~5 days for force carbing a keg), as both of those are ~100 times longer than the go-flat time. Either something else is going on, or the rate is much slower for absorption for some reason.

When you're watching bubbles escape from a beer into the atmosphere, it's not really the opposite of what happens when bottle conditioning. Yeast release CO2 as individual molecules. It's not like a huge cluster pops out that immediately would appear as a bubble. Since "dissolved" means the individual molecules intermingling with the solvent, doesn't it follow that CO2 expired by the yeast is already by definition "dissolved"?

 

[zeg]

When you're watching bubbles escape from a beer into the atmosphere, it's not really the opposite of what happens when bottle conditioning. Yeast release CO2 as individual molecules. It's not like a huge cluster pops out that immediately would appear as a bubble. Since "dissolved" means the individual molecules intermingling with the solvent, doesn't it follow that CO2 expired by the yeast is already by definition "dissolved"?

I'm not sure what's happening on the microscale when yeast produce CO2. It is, at least in some sense, dissolved, but the question is whether it's in a stable equilibrium. If it's not uniform, it may take some time to diffuse through the solution and into the headspace to reach an equlibrium pressure. It seems at least possible that it takes a bit of time to reach a stable solution. This is a bit out of my league.

In the case of bubbles escaping, this happens even when the CO2 was fully dissolved. It's not necessarily very different from yeast producing it---by some process, a nucleation point develops and CO2 molecules cluster around it. Again, I don't know enough about what is going on when this happens in a disturbed equilibrium situation to know whether it's comparable to CO2 freshly output from yeast.

 

[Bobby_M]

I agree that the CO2 in solution will take some time to diffuse out into the headspace to get the concentration equalized. The whole debate is really about whether most or some of the CO2 produced somehow migrates to a higher concentration in the headspace and that part of the reason bottle conditioning takes time is that it has to magically find its way back into solution. On the contrary, I contend that while yeast are producing CO2, the concentration is always higher in the beer than the headspace until equilibrium is reached. It's the exact opposite of what happens during force carbonation.

 

[zeg]

Well, my interest goes deeper (and less useful, probably) than the original question.

On that subject, though, I don't really disagree with you. I'm a bit reluctant to fully agree because I don't have a lot of faith in my intuition about systems like this.

If we assume you're correct, and that the CO2 is instantly in solution, there are still questions to resolve. There is a large amount of anecdotal (and perhaps better) evidence that it takes a while for carbonation to become stable. For example, there's Revvy's frequently posted (maybe even in this thread) gushing carb video. If these experiences are correct, then something is happening beyond simply producing the CO2. It's possible that the evidence is simply flawed, though. It's hard to collect proper data about brewing, especially in homebrewing processes, and there are plenty of examples of even experts drawing incorrect conclusions. But I'm rather inclined to trust that the anecdotes at least indicate *something* is changing.

One possibility, along the lines of what you're suggesting, is that in fact the CO2 is instantly in solution in the beer, but requires time to diffuse out and equalize the pressure in the headspace. This might cause the beer to be initially *more* supersaturated because some of the CO2 that will later 'ffft' out when you open the bottle is still in solution. If that's true, it could explain the gushing behavior. Now that I've suggested this, I'll shoot it down: my rough calculations suggest that the quantity of CO2 in the headspace is less than 1% of that in the beer, and that the difference between equilibrium at various carbonation levels is even smaller. I don't think that's enough CO2 to make any difference. So I'm not sure what's going on.

 

[tj218]

This is quite interesting. I appreciate all the effort at giving me an answer!!! THANKS!