Is it possible to have to much headspace in a carboy? If there is too much space could the beer be ruined from oxygen? A friend pointed out to me that my carboy is to big for 5 gallon batches and this is likely to happen. Here is a pic..
Too much headspace in carboy?
- Thread starter jakis
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Lots of people have those same carboys for 5 gallon batches, myself included. You'll be fine. The CO2 produced during primary will push out all the O2.
BTW you could always brew 5.5 gallons and after the trub is left behind end up with 5 gallons in your bottling bucket.
BTW you could always brew 5.5 gallons and after the trub is left behind end up with 5 gallons in your bottling bucket.
harry_the_face
Well-Known Member
Fermentation crates CO2, which heavier is than air, so within a few hours there is a layer CO2 covering and protecting the beer. So long as you are not moving or sloshing your carboy the liklihood of air contact is none. I would guess that after about 12 hours of fermentation that the head space is totally CO2 and all the air has been pushed out.
I will tell you that I ferment in a small chest freezer and a few days into fermentation I was going to wipe up some overflow from the bottom of the freezer. I had to bend over and put my head in the freezer to get to the bottom and as I was wiping took a breath or 2 and very quickly felt like I was going to pass out. The entire freezer was filled with CO2.
Don't worry about it. IMO
I will tell you that I ferment in a small chest freezer and a few days into fermentation I was going to wipe up some overflow from the bottom of the freezer. I had to bend over and put my head in the freezer to get to the bottom and as I was wiping took a breath or 2 and very quickly felt like I was going to pass out. The entire freezer was filled with CO2.
Don't worry about it. IMO
Devilsnight
Well-Known Member
You don't want any headspace in your secondary, primary is fine though. Your good here.
microbusbrewery
Senior Member
+1 what everyone else is saying. Ideally you want to minimize headspace but 99.9% of the time, your scenario isn't going to be an issue because of the CO2 that's being produced. As long as you're not pulling the bung out a couple times a day, you'll be fine. The only time I might be a little concerned would be if you're doing some extended bulk aging, but in most cases you'd want to rack to a smaller secondary anyway
Some yeasts need the extra head space in some beers. My ESB with S-04 yeast re-hydrated needs 30% head space for all the krausen. Co2 absorbs the oxygen rather than displacing it. So it'll take some hours to absorb it before it start bubbling the airlock & displacing excess gases. It should be OK if fermentation started in a reasonable amount of time.
I got that one from a previous discussion on this very subject where a science-minded type member corrected me...he blinded me...with science! 
It does make sense when you think about it. I always thought the Co2 pushed out the o2. But he stated otherwise, so...?...
It does make sense when you think about it. I always thought the Co2 pushed out the o2. But he stated otherwise, so...?...
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Gasses will readily mix, but pretty sure they retain their original molecular structure. I’d like to see a link to that "science".
Now if you had said, "Yeast absorbs the oxygen rather than displacing it. . . ."
It's in an old thread on here somewhere. I don' remember exactly when, but this year anyway.
Gasses don't absorb, they mix.
So yes, he (the science-minded member) is correct, CO2 does not just push out the air from underneath and creates a "CO2 blanket." It mixes, mostly, with the air that's in the headspace. Thus the amount of CO2 in that air, which is already an N2/O2/CO2 mixture, increases, while the excess volume of that gas mixture leaves through the neck or airlock. There will be some stratification while there's active CO2 production.
So yes, he (the science-minded member) is correct, CO2 does not just push out the air from underneath and creates a "CO2 blanket." It mixes, mostly, with the air that's in the headspace. Thus the amount of CO2 in that air, which is already an N2/O2/CO2 mixture, increases, while the excess volume of that gas mixture leaves through the neck or airlock. There will be some stratification while there's active CO2 production.
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So, you're saying that CO2 absorbs O2 and turns it into more CO2?
Pretty sure if that were true. we'd all be dead. :cross:
I'm pretty sure he said it absorbs it, but I could be miss-remembering at my age. Mixing could be the more accurate expression.
I'm no research scientist or anything like this guy was/is. But it made sense at any rate. It'd be interesting to study the actual effect to determine exactly what is happening though.
william_shakes_beer
Well-Known Member
So, just to be the fart in the space suit:
If yeast need oxygen to reproduce, and all the oxygen in the head space is pushed out in the first hour, the only oxygen available to the yeast is that dissolved into the beer by my shoshing around just after the pitch. True?
If yeast need oxygen to reproduce, and all the oxygen in the head space is pushed out in the first hour, the only oxygen available to the yeast is that dissolved into the beer by my shoshing around just after the pitch. True?
That's the gist of it, yes. Dissolved o2 is used by the yeast during the reproductive, or "lag" phase. But that guy should filled the small container with the Co2 1t, in my opinion. He seemed to pour it onto the flame, extinguishing it.
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The dude in the video says that CO2 will remain in the bottom of the container unless disturbed. This is totally incorrect. The displacement is a temporary condition. Gasses will readily mix after initially combined regardless of outside influence.
grainbill
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The only issue I see with having a lot of head space is that with some batches you will have a fair amount of krausen. It is my understanding that it is better to have the krausen exit the carboy through your blow off tube instead of have it settle back into your batch. (Otherwise, why have the blow off tube in the first place) Then again, it could just be personal preference....
Although it's been a few years since I've used basic chemistry, I have a minor in chemistry with my BS in bio. CO2 doesn't absorb O2. If it absorbed oxygen, it would become CO3 or CO4, which are unstable oxides that wouldn't be found in beer, and wouldn't be formed without energy input.
What you may be referring to is that as oxygen is used by yeast in aerobic respiration, CO2 is produced. Then as anaerobic fermentation begins, more CO2 is produced. As the O2 is being used up in solution, the O2 in the headspace will be dissolved (as well as pushed out by the increasing amount of CO2 in the headspace) in solution until all the oxygen is used up. So, in reality CO2 is not absorbing oxygen. However, the process that is creating the CO2 by aerobic respiration is using O2 (which could have been referred to as absorbing).
Some of the oxygen in the headspace will dissolve into solution and some will be pushed out by the CO2 from yeast activity. So (assuming there is no air leak in the air lock/lid), the oxygen dissolved in solution will be used up, and then whatever little bit of oxygen left in the headspace will get pushed out and some will be dissolved back into solution. After the oxygen is used up, even sloshing won't increase the oxygen in solution, as there is none in the headspace (again, assuming no leaks).
chickypad
lupulin shift victim
Yes, a better video is linked by aj in the second page of this thread. Sorry, can't remember how to imbed a video myself. His explanation is worth reading anyway.
So the gasses diffuse, rather then absorb or mix. Good explanation.
However, even with "no leaks", there is never ever going to be 100% c02 in the headspace. Sure, the majority of the gas in the headspace may be c02, but as fermentation slows, the laws of physics state that equilibrium returns. Remember that rubber bungs and such are not non-permeable. Oxygen can enter the fermenter even through the liquid in the airlock- and those plastic airlocks are oxygen permeable.
Read this study on better bottles (but go to the airlock and closures part) to see what I mean: http://www.mocon.com/pdf/optech/Closures - Oxygen Passage Study.pdf
Still, the beer will be safe in there at least for a couple of weeks after fermentation slows. At that point, it would be best to package the beer or rack to another vessel to eliminate headspace.
Diffusion is, for our purpose here, just another word for mixing of gases in a liquid, so in other words, the gas diffuses into the liquid, which means it mixes with the liquid. Absorption does take place. Both O2 and CO2 are absorbed by the liquid. However, it's just a matter of what is absorbing (or absorbed by) what.
The gases (CO2 and O2) are absorbed by the liquid (wort/beer).
The gases diffuse in the liquid until they're either chemically changed by aerobic respiration (O2) or they leave solution as a gas in the headspace (CO2 and to a very small extent, some O2).
As the gases (CO2 and O2) are diffusing into the liquid, they are mixing with each other.
Well, the question here seems to be how much mixing happens in the head space as some small part of them is absorbed into solution to reach equilibrium. This would govern how long/how much is absorbed into solution versus the amount in the head space that could allow infections to occur in a given amount of time if any nasty's are present. However small their actual numbers might be?
Yes, certainly. I was speaking from a theoretical point of zero oxygen exchange. The discussion then becomes how much air exchange actually occurs, and how much does that affect the taste of beer. From what I know, that's fairly negligible for the short term for most ales.
And truthfully, I was surprised at how much air exchange occurred through those air locks. I think I may invest in some different stoppers for secondary fermentation after reading that link you provided. Thanks!
Yeah, I agree. It's surprising that the results came out as they did with some. I got the buono vino plug for my 6 gallon BB. That orange cap thing's results don't surprise me though. That thing fits snug, but not tightly. They should've tested bucket lids with & without seals & the different styles of airlock grommets as well. I'd like to see that, as I have two different grommet styles in use. Spraying Starsan on the airlock stem lubes it for easy installation. But when the Starsan dries, it sort of glues it in place, improving the seal. Just like we did with vacuum lines at the engine plants.
Another question related to this. I'm supposed to dry hop this brew with Citra Hops. It's say dry hop 3-4 days before bottling. So the only time I am going to dry hop tomorrow night and bottle Saturday. Should that be fine? Also, to dry hop I was just gonna take off the airlock, put the hop pellets in and then replace the airlock with a sanitized one. Is that fine? Will I run the risk of oxygen in my beer by dry hopping this way?
3-4 days dry hop would be OK. But I prefer 5-7 days for more aroma that lasts longer. Dropping the pellets through the airlock grommet would be tedious at best. And make more floaters in the beer, imo. I like hop sacks for dry hopping to keep things cleaner.
After reading the study you linked, I bought enough of the red rubber caps to fit all of my carboys, to replace my traditional (leaky!) bungs. I also bought 4' of solid PET rod for my beers and wines that will be stored for long periods after fermentation.
Thanks again for posting that study!
That should be fine, since it's very short term. I typically dry hop for 3 to 5 days for most beers, at room temperature.
MagicMatt
Brewmathemagician
I really like this report, but I'm starting to wonder about the accuracy of some of their measurements. For instance, they say the total volume with the Buon Vino bung is 131cc, yet the "orange cap" is only supposed to yield 129cc?
The bung actually goes INTO the neck of the carboy by at least 1/4" - so how is it that the orange cap, which fits OVER the neck (and actually provides an added volume in that of the two stems) is somehow less of a volume than that of the bung?
You misread the study. The red cap volume was 159 cc, as compared to the Buon Vino volume of 131 cc.
Errr, whoops. I misread your post. Orange, not red...
