Carboy Bung (Silicone) - Breathable #10

Carboy Bung (Silicone) - Breathable #10

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Fits PET Carboys. A breathable Silicone stopper that acts as both a stopper and an airlock. Unique design allows CO2 pressure to escape but keeps Oxygen and airborne contamination out. Quickly became our stopper of choice for wine. Used by numerous commercial wineries. Also has great application for beer ferments: Will create a vacuum if fermenting wort cools (as opposed to pulling water in from your traditional airlock.) Air tight seal is great for extended fermented lager when CO2 production is still present but very slight.

Item # FE491
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Availability California - In Stock
Pennsylvania - In Stock
Weight 0.30 LBS
Community Q&A

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Browse 5 questions Browse 5 questions and 27 answers
Why did you choose this?
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use them...love then
Marion K on Feb 24, 2023
It's not super tall and low maintenance
sarah d on Sep 12, 2022
use them...love then
Marion K on Feb 24, 2023
Recommended by Doin the Most you tube video
James W on Sep 24, 2022
It's not super tall and low maintenance
sarah d on Sep 12, 2022
WIll try to get rid of airlock
Lizeth D on Aug 17, 2022
As an airlock for the 1 gallon fermonster
Jeff D on Aug 8, 2022
have some, like them
Marion K on Jul 29, 2022
For trials to see how well it works.
Stephen C on Mar 16, 2022
Seems to be better than an S or 3 piece airlock
Jordan H on Jan 3, 2022
I love these things for me PET carboys. They are expensive but they are set and forget, they don't break, and they provide a low profile.
Zachary J on Oct 26, 2021
Have used before - need more.
Doug H on Sep 29, 2021
Love these
BENJAMIN S on May 5, 2021
Low profile, less hassle.
landon gellert on Apr 6, 2021
Heard good things and less hassle
landon gellert on Mar 27, 2021
Everett S on Feb 26, 2021
I want to bulk age some high ABV beverages and don't want to worry about keeping water in the airlock. Also, I've been brewing a lot of lagers lately and this is supposed to keep oxygen out during cold crash.
Matt Burns on Feb 9, 2021
Does not need water
Joe Keesling on Jan 15, 2021
Single closure item sounds interesting.
Bryan A on Dec 29, 2020
Works well, never runs dry like traditional airlocks
Doug H on Dec 10, 2020
I need a plug for my barrel
thomas r on Sep 1, 2020
Great for secondary fermentation, crashing, moving and storing fermenters. Also it's easy to sterilize.
Douglas I on Aug 20, 2020
Should fit plastic 5gal water bottles
snicholsissupercool on Aug 14, 2020
airlock alternative
Cristina C on Aug 5, 2020
Easier and safer fermentation
bc-bruce on Jun 20, 2020
Roland B on May 28, 2020
Doin the most told me to get them
Timothy S on May 28, 2020
Lucas A on May 19, 2020
I need @10 air traps
Perry A on Apr 23, 2020
fits PET and is low profile
Adam Reynolds on Feb 25, 2020
My son wanted it for Christmas
Karen Y on Dec 5, 2019
I have tried a bunch of different ones so far, and these by far work the best.
David B on Sep 13, 2019
Plan to use them on The plastic Wide Mouth plastic carboys
Dave W on Dec 18, 2018
Easy to use
Robert B on Sep 6, 2018
I use PET carboys that use a #10 bung. I accidently bought the smaller one (for carboys) a while back. Pet carboys flex a little when you move them around and fluid from your air-lock can be sucked into the carboy. Not good. I use my small breathable bungs on gallon jugs. (so I did find a use for them)
Karyl N on Apr 16, 2018
Recommended by Doin the Most you tube video
James W on Sep 24, 2022
WIll try to get rid of airlock
Lizeth D on Aug 17, 2022
Do you have anything that will fit a 1 gallon carboy?
Robert Davis on Oct 18, 2023
Will this fit on a 30L Speidel fermentor in place of the air lock?
Todd Girouard on May 30, 2019
BEST ANSWER: The #10 Silicone Bung does not fit on the 20/30L Speidel fermenter.
Looks like it's made for use with wines, will this work well for fermenting all types of beer too?
landon gellert on Apr 2, 2021
BEST ANSWER: That will depend on the amount of pressure your container is under, really. I use these for secondary wine racks and the pressure is much less than the initial fermentation. Even so, I have still had a few blown out of the container. If your pressure is lower I highly reccomend these.
Can I use it to brew beer in a FerMonster Carboy? Or is the potential for a vacuum a problem?
landon gellert on Apr 2, 2021
BEST ANSWER: Since the FerMonster is plastic there is not really a big issue with vacuum. The fermenter will slowly draw in at the sides until there is enough vacuum to break the seal on the bung.
How do you clean these?
jdub on Mar 4, 2021
BEST ANSWER: Very hot water upside down and flowing thru, then followed by either a brand name chemical cleaning (or metabisulfate) and/or thin flexible brush with top cap gently pulled back.


4.8 / 5.0
12 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Rated 5 out of 5
Never have to worry about changing the water or running dry again. Where have these been all my life?
February 1, 2023
over 3 years ago
Rated 5 out of 5
My Secret Weapon
These bungs are great! I’ve used them with twelve-liter Better Bottles over several batches of both ales and lagers without any problems. Unlike a standard airlock, you don’t have to worry about sucking water from the airlock into the fermentor if you move it around or crash cool your beer, and these bungs have fewer parts so they’re easier to clean. You do have to be careful when crash cooling ales because the large temperature differential can create enough pressure to warp a plastic fermentor like a Better Bottle. However, I’ve found that you can prevent this from happening by pulling up the top rubber seal for a few seconds after cold crashing is complete to relieve the pressure. The amount of oxygen you introduce seems to be negligible; over dozens of batches this hasn’t been an issue.
December 20, 2022
over 2 years ago
Rated 4 out of 5
Buy with a TILT
I tried it and I’m sure it’s good and it does work, but I cannot tell the level of fermentation because I cannot see the bubbling action on the airlock without a TILT
September 28, 2022
over 2 years ago
Rated 5 out of 5
So far so good
I have the breathable silicone bung in a 3 gallon PET carboy of a melomel in secondary. Fit is good if the mouth of the carboy is dry otherwise it likes to stand up.
January 24, 2022
over 2 years ago
Rated 5 out of 5
Vents While Keeping O2 Out
Simple, durable, effective venting bung.
January 14, 2021
over 5 years ago
Rated 5 out of 5
Great fit and quality.
This product was a perfect fit to my plastic carboy and quality construction and material.
May 18, 2020
over 4 years ago
Rated 5 out of 5
Snug and efficient.
Nice low profile allowing fermenting carbon to fit on shelf. Won’t ever run dry again.
April 14, 2020
over 4 years ago
Rated 5 out of 5
This product is a great acquisition for my brewery since it helps me keep track of my beers in wooden cask with no effort in a sanitary fashion.
Great product. Sanitary stopper with flexibility, durability and washability makes this choice a perfect one.
December 23, 2019
over 4 years ago
Rated 5 out of 5
Love these
I fell in love from the first moment I used it in my Fermonster. Seals perfectly and easily. No need to monitor sanitizer level over long fermentations. No bubbling sound. No risk of suck back.
May 14, 2018
over 6 years ago
Rated 5 out of 5
Much better seal than the other barrrel bungs.
April 13, 2018
over 6 years ago