Carboy Caps are NOT Air Tight... What?

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Scut_Monkey

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Below is a link to a relatively unknown by me website that states that carboy caps are not air tight and should only be used during primary. I have never heard this nor do I believe it. I do know that some people struggle with getting a good seal with them with better bottles while others have no difficulty at all with using them on a BB. Just thought I would throw this out there and see what everyone else thinks. I get a great seal on my carboy with one.

Glass carboys - Gallon jugs - Demi johns - Wine making supplies - Beer making
 
I've noticed that caps come in different sizes. I've bought from AHBS, my LHBS, and other places. For the same exact color, some fit snug, some fit loose, some don't fit at all. This applies to both the orange and maroon ones (I have glass and BB carboys, so I need various sizes).

They must come from varying manufacturers or something. Thus, take people's anecdotes and experiences with these things with a huge grain of salt. Even if they say: "my orange one fits my BB perfectly," you don't know WHERE they got their cap from, so you might not have the same experience. Some people need rubber bands to get a tight fit, some don't fit at all. It's a jungle out there!!!

I've tried to figure out which of mine fit which carboys, and mark them with a permanent marker accordingly...
 
yeah, +1 on that. the orange fit my BB, but the maroon ones fit much more snug. i've also noticed different sizes with the orange. I'm sure the maroon differ also but I bought mine from one store in one order, while the orange were bought from various stores at different times.
 
Neither are some bucket lids, or stoppers in carboys, or the gasket where the airlock goes into...that's why many airlocks don't bubble...But the good news is things don't need to be air tight. In fact that's what an airlock is for to void built up pressure so you don't paint your ceiling with your beer.

See, the thing is fermentation makes co2...which pushes outward, and if co2 is getting out, then nothing else is getting in...including air.

The only time we really need something airtight (actually co2 tight) is in the bottle or the keg....because that is how our beer get carbonated, the co2 cannot escape so it permeates the beer instead.

If you look around you will see that a lot of brewers don't use airclocks, or lids, or stoppers at all, some use tinfoil instead or even place a piece of plexiglass on top of their buckets instead of the airtight lid...any co2 that needs to get out, will....and the positive pressure from the co2, keeps anything else from getting in.

Nothing to worry about with carboy caps, really....
 
Revvy has it right.... I don't have a single carboy cap that IS airtight. However, it doesn't matter a single bit.
 
Revvy has it right.... I don't have a single carboy cap that IS airtight. However, it doesn't matter a single bit.

Even when in a secondary for either a short (3 weeks) or extended period of time? I can't imagine there would be a ton of CO2 coming off but I also can't see a ton of atmospheric air entering in through a leaking carboy cap.
 
Revvy has it right.... I don't have a single carboy cap that IS airtight. However, it doesn't matter a single bit.

I've had an issue with them not being airtight. It matters to me, because I'm also a winemaker and I have 5 gallons of oxidized wine from trusting those carboy caps. The other carboy was fine. Both caps seemed to fit well, but apparently one didn't. I'll never trust them again.
 
Even when in a secondary for either a short (3 weeks) or extended period of time? I can't imagine there would be a ton of CO2 coming off but I also can't see a ton of atmospheric air entering in through a leaking carboy cap.

C02 is heavier than air, its not really going to be a problem. Your not trying to get a hermetic seal, your trying to keep nasties from floating down and IN to your beer. Many use foil as a cover. Air-tight is not nessicary.
 
I've had an issue with them not being airtight. It matters to me, because I'm also a winemaker and I have 5 gallons of oxidized wine from trusting those carboy caps. The other carboy was fine. Both caps seemed to fit well, but apparently one didn't. I'll never trust them again.

Does wine not off-gas co2 like beer does? I know nothing about brewing wine.
 
Does wine not off-gas co2 like beer does? I know nothing about brewing wine.

It doesn't really matter if it's wine or beer or anything, it's all about the pressure difference.

It's true that during primary fermentation "air tight" storage isn't needed, or desired... however if you are aging a big beer (i.e. saison, barleywine) or wine or mead, and you are going to leave it for a few months or longer, I wouldn't trust anything other than an airlock, simply out of fear of oxygen exposure.
 
I have three of these caps 2 fit the BB and 1 is too small . But the plus side is that the smaller on fits the US plastics 15 gallon barrels small bung hole perfectly
 
It doesn't really matter if it's wine or beer or anything, it's all about the pressure difference.

It's true that during primary fermentation "air tight" storage isn't needed, or desired... however if you are aging a big beer (i.e. saison, barleywine) or wine or mead, and you are going to leave it for a few months or longer, I wouldn't trust anything other than an airlock, simply out of fear of oxygen exposure.

I think you missed the point of my question. If wine yeast is producing CO2, then you have 2 things happening.

1. Co2 produced is causing a positive pressure situation IN the fermenter, keeping O2 out
2. Co2 produced is forming a blanket of co2, which is denser than the surrounding air, keeping O2 out.

Either way, if wine yeast is producing Co2 and its offgassing, then the airlock does not NEED to be tight and you have no need to worry about oxygen exposure.

However, we should all do what we are comfortable with.
 
for me it was always a matter of the drilled stopper costs 32 cents, the caps are a few dollars more... ;)
 
for me it was always a matter of the drilled stopper costs 32 cents, the caps are a few dollars more... ;)

I had more than a few stoppers come off.. especially after they were soaked in sanitizer since it made them a little slippery. I went to the carboy caps and have been very happy. I know mine are air-tight as I've actually transferred beer using CO2 from one to another. I don't do it anymore though, not sure if the pressure is okay for the carboy.
 
I know this is an old thread but I just bought three of these (two 5s and a 6.5) and the 5s are not airtight. It's to the point where If I put a airlock on there are not bubbles. But when I fit it with a bung there are bubbles every .5 second.
 
I know this is an old thread but I just bought three of these (two 5s and a 6.5) and the 5s are not airtight. It's to the point where If I put a airlock on there are not bubbles. But when I fit it with a bung there are bubbles every .5 second.

But it doesn't really matter...bubble mean absolutely nothing, as does the rate if any that they bubble.
 
I disagree a bit. The point of a bung and airlock is that it is airtight. This shows that it is not. Also, the bubbles are a very helpful indicator to the brewer/wine maker. A lot of people like to know how strong their brew is fermenting at any giving time.
 
I disagree a bit. The point of a bung and airlock is that it is airtight. This shows that it is not. Also, the bubbles are a very helpful indicator to the brewer/wine maker. A lot of people like to know how strong their brew is fermenting at any giving time.

And how does an airlock that may or may not bubble, or can bubble slow, or fast or not at all, can start and stop due to changes in barometric pressure, temperature, or whether or not the cat or vacuum cleaner bumped into it, help you to know how "strong" a brew is fermenting at any given time? Half the time my airlocks NEVER bubble. And sometimes the lowest gravity beer will have an airlock blowoff whereas I could be brewing a barleywine that barely bubbles?


Bubbling and fermetnation are NOT the same thing. And you really need to separate the two ideas. Airlocks tell you the WHAT is happening, that co2 is or isn't getting out of the fermenter....but they aren't telling you the WHY. If it's fermenting or not, or off gassing or not. If it's done or not....

A HYDROMETER is the only indicator of how a beer/wine is doing at any given time. An airlock is purely a vent, a VALVE to release built up co2, it's not a "magic fermentation gauge."


Airlock activity is irrevelent. Just gravity points on a hydrometer.

The rate or lack of or whether or not it bubbles at all, or if it starts and stops has more relation to the environment the fermenter is in, rather than fermentation itself. All it is is a vent, a valve to let our excess gas, especially co2, nothing else. It's not a fermentation gauge whatsoever.

And the only TRULY airtight fermenters out there are if you ferment in a keg or a conical, something that can contain the pressure of fermentation.

Contrary to what you may think, neither a bucket OR a carboy with a bung is airtight. As I stated above you don't want it to be airtight, unless it's a keg or a Stainless conical, unless you like beer/ wine on your ceiling.

The airlock is one of the most superfluous things in brewing, that new brewers seem to put the most stock in.

A lot of folks don't use them at all. In fact many folks with arthitis and other issues don't snap the lid down on their buckets anyway, and may folks just put tinfoil, plastic wrap, metal cookie sheets or even plexiglass sheets on top of the bucket instead. It's really not crucial to be tight.

Some folks use blowoff tubes exclusively...

The newest thing, that is replacing airlocks on carboys is this.

vented_stopper.jpg


These food grade silicone stoppers feature several vent holes lightly sealed with a silicone top flap. Gases can escape, but cannot get in. Just put the stopper on your carboy, and forget it. No worries about evaporation or water getting into your fermenter. This #10 size is pictured at right above, and fits all Better Bottles, and other containers with a 1.75" opening.

http://www.fyurl.com/rr.php?c=2&sit....com/10-VENTED-SILICONE-STOPPER-P2667C94.aspx

Homercidal posted the other day that he was just at a commercial brewery in Traverse City where they FERMENT their beer with plastic wrap on top of the fermentation vessels. And one of our mods posted recently that he just uses loose fitting lids on his fermenters.

I've said it over and over and trolls like to try to get me, or even accuse me of lying (which I don't get why I would lie about something like this) but over the years of LOTS of batches of ALL SIZES and BOTH carboys and buckets, better bottles or glass, carboy caps or bungs, new buckets old buckets, s-types and 3 piece, I get about 50% airlock failure rate (but 100% success rate of fermentation) and it's any number if things, usually simply a non tight seal in the bucket or carboy or grommet....but to me the reason doesn't matter....the point is just trying to glance at an airlock and know what the beer is doing, just is NOT accurate.

My belief is that 1 occurrance is an anamoly, 2 may be a coincidence, BUT 3 or more occurance is an epidemic...and that's the case for folks relying on airlocks all the time, to me if 1 brewer comes on saying his airlock is not bubbling, AND he takes a reading and finds fermentation is going fine, that's an anamoly...

But DAILY on here there are at least 10 threads stating the exact thing...so MAYBE there is something to this idea that airlocks can be faulty. AND if they have the potential to be faulty, then how can we trust them to tell us what's going on?

You can quibble about it all you want, or deal in semantics, but we deal in sheer volume of users on here, and daily we have airlocks not bubbling, and many of them where a gravity reading indicates that fermentation is happening beautifully.

And yes, in an IDEAL situation (like let's say fermenting in a keg with a tight seal and no leak from around the airlock) the airlock SHOULD bubble 100% of the time (providing there's not too much headspace.) If more co2 is created than can be contained in the spavce of the fermenter, THEN an airlock should bubble....because an airlock is a valve.

But MOST of us don't have IDEAL situations, and rarely is a plastic or glass fermenter airtight- it really isn't supposed to be anyway...SO we aren't in the best situation to have IDEAL 100% accuracy of an airlock...


So that's why it's a good idea NOT to relie on or stress out about what it is or isn't doing. Just realize that airlocks bubble or they don't, they start, they stop, they bubble fast, they bubble slow, and they bubble or don't whether fermentation happens or not.

Like I said, the only accurate thing that will tell you what your beer is or isn't doing, is taking gravity readings.

The only way to truly know what is going on in your fermenter is with your hydrometer. Like I said here in my blog, which I encourage you to read, Think evaluation before action you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right diagnostic tools before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in....
 
I don't want my fermenters to be airtight so that my airlock can bubble but I do want it to be airtight for extended aging when there is not a constant positive CO2 pressure in there. This is especially true for sours that do NOT benefit from excess acetic acid flavors. Of course, this might be a tangent.
 
Carboy Caps are NOT Air Tight... What?

All dead horses aside and getting back to the original (and very old) post that started this. Take one of those heavy rubber bands, the type they use on lobster claws. Double it up and put it around the recess in the carboy cap. Like magic, you’ll defy Revvy science and have a sealed fermenter.

If an airlock is nothing more than a valve, a hydrometer is nothing more than a fishing bobbin with lines on it. Used properly, both will provide you with information.

In other news. The permanent CO2 blanket is a myth. Airborne contaminate only fall straight down when the air is stagnant. Damn! What’s up with all the fruit flies this year. Open fermenting. Yeah right! I’ve got two dogs and a damp basement.
 
All dead horses aside and getting back to the original (and very old) post that started this. Take one of those heavy rubber bands, the type they use on lobster claws. Double it up and put it around the recess in the carboy cap. Like magic, you’ll defy Revvy science and have a sealed fermenter.

If an airlock is nothing more than a valve, a hydrometer is nothing more than a fishing bobbin with lines on it. Used properly, both will provide you with information.

In other news. The permanent CO2 blanket is a myth. Airborne contaminate only fall straight down when the air is stagnant. Damn! What’s up with all the fruit flies this year. Open fermenting. Yeah right! I’ve got two dogs and a damp basement.

I just stumbled upon this thread after having issues with the carboy cap I just received in the mail. I used a thick rubberband that came off of a bunch of collard greens and that seemed to do the trick.
 
Mine do not fit my carboys either. No worries, I like my rubber stoppers and airlocks, unless I have vigorous fermentation which warrants a blow off tube.
 
I agree with Revvy. The purpose of the airlock is to let the waste product out (CO2) and keep the ickies out. It should be a good seal, but I don't see how it could possibly be airtight. The airlock does let air out but does not let dust, mold spores, etc. into the vessel. I've brewed many a batch with just a rubber band or aluminum foil on a shaky cap or bung, and it's always turned out fine.

Now, if I could only keep everything from slopping all over the floor!
 
All dead horses aside and getting back to the original (and very old) post that started this. Take one of those heavy rubber bands, the type they use on lobster claws. Double it up and put it around the recess in the carboy cap. Like magic, you’ll defy Revvy science and have a sealed fermenter.

If an airlock is nothing more than a valve, a hydrometer is nothing more than a fishing bobbin with lines on it. Used properly, both will provide you with information.

In other news. The permanent CO2 blanket is a myth. Airborne contaminate only fall straight down when the air is stagnant. Damn! What’s up with all the fruit flies this year. Open fermenting. Yeah right! I’ve got two dogs and a damp basement.

HaHa!!!! Just reading through an old thread and see you've used my quote in your sig line! I'm honored! :mug:
 
BTW,
I don't question what Revvy knows, because he knows his stuff, but my experience is that in my better bottles, with drilled stoppers and blow off tubes that I switch to S-shaped airlocks later in fermentation...I'm closer to 100% air tight. Not sure why he gets such a high failure rate.

Between what I see in the better bottle and what I hear coming from the airlock/blowoff jar, I keep a close eye on fermentations.

I know I know...there's a hundred other reasons why an airlock may or may not bubble, but lets be honest, there is an amazingly high correlation between CO2 production and fermentation.

Also this concept of a "blanket" of C02 over finished beer is a little misleading. Because the blanket can be disturbed by a number of things and it's not a solid, it's a gas. O2 can absolutely make it's way into your beer if there is O2 in your fermenter, so I like to avoid that situation as much as possible after fermentation has began.

Next to fermentation temperature related off flavors, the most common off flavor in homebrews is oxidation. There's a reason the VAST MAJORITY of breweries in the world are doing closed fermentations..because that "blanket" isn't as reliable as some of you seem to think it is.
 
Wow, not sure why I didn't think about a rubber band around the carboy cap. To the beer cave!
 
[...]Also this concept of a "blanket" of C02 over finished beer is a little misleading. Because the blanket can be disturbed by a number of things and it's not a solid, it's a gas. O2 can absolutely make it's way into your beer if there is O2 in your fermenter[...]

Completely true, but just a bit short: the CO2 "blanket" is a unicorn, a complete myth. It simply cannot exist in conditions short of a lab.

Which is a good thing, else we'd all be dead...

Cheers!
 
I agree. For protecting our wort or beer it's a myth, but not a complete myth. CO2 can be poured and will flow to the bottom of a container, but diffusion is pretty quick. There's a report about a bunch of people and livestock being killed when a cloud of CO2 was released. It blanketed for long enough to suffocate them.
 
So I bought a plastic conical. It's got a big screw on cap, like 12" big. The cap screws onto a big collar that was just screwed onto the conical with stainless screws. I was going to seal it with food grade silicone caulk. That would require me to carefully seal all the way around this cap collar, then put another bead around it in a way that the cap would hit it flush and seal. Then I was going to drill a hole for the airlock grommet and use an airlock. Ugh. After reading all four pages of this it sounds like I should just not even worry about it. Thoughts?

I'd like it to bubble because I like to watch it and check it several times a day to get a feeling for when it is about done and ready to transfer to secondary. View attachment ImageUploadedByHome Brew1418093691.030525.jpg
 
I can't really answer your question except to say that a nice O-ring at the seat of those threads in the lid might do 90% of what you want you to do.

My other comment is off topic :off: Where'd you get that conical?

Happy Brewing!

ZB
 

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