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Big Mouth Bubbler® - 6.5 Gallon Plastic Fermentor


SKU# U41965


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Big Mouth Bubbler® Plastic is a virtually indestructible fermentor, equipped with 3” thick anti-flex ribs, a punted bottom and decreased base diameter for extreme strength and durability. Its smaller footprint preserves precious brew cave space and allows for convenient storage inside a standard brewing bucket.

Included: Big Mouth Bubbler® - 6.5 Gallon Plastic Fermentor, single-port universal lid.
Required: Small Universal Stopper & airlock. Configure options below.

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Big Mouth Bubbler Plastic - 6.5 Gallon   +$29.99
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Big Mouth Bubbler™ - 6.5 Gallon Plastic Fermentor

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  • Big Mouth Bubbler® - 6.5 Gallon Plastic Fermentor
  • Big Mouth Bubbler® - 6.5 Gallon Plastic Fermentor
  • Big Mouth Bubbler® - 6.5 Gallon Plastic Fermentor Lid


Product Details

Superior to a carboy, Big Mouth Bubbler® Plastic prevents off-flavors by enabling you to keep the lid on during testing and transfer, avoiding exposure to oxygen with standard-sized ports that can accommodate most fermentation-monitoring equipment.

The punted bottom promotes crystal-clear beer by efficiently settling out yeast from finished fermentations. Graduation marks make volume measurement instant and effortless. And, of course, its revolutionary wide mouth eliminates the nightmare of cleaning and sanitizing by giving you direct hands-on access to attack crusted krausen, while simultaneously offering unlimited flexibility in dry-hopping and flavor additions.

*The new Big Mouth Universal Lid (included) fits all Big Mouth Bubbler® Fermentors. The Big Mouth Bubbler® Universal Lid is just like a traditional carboy bung, only bigger! Just as easy to sanitize and set in place too. Ribbed silicone rings ensure a positive seal to keep out pests, while the non-threaded design allows the lid to move preventing an out-of-control fermentation from dangerously pressurizing your fermentor.

The optional Dual Port Lid allows for the use of a temperature controller probe. The ThermoStar Dual-Mode Digital Temperature Controller with optional 12" stainless probe ensures precise and repeatable fermentation temperatures!

Lid port works with our Small Universal Stopper or a standard 6.5 rubber stopper.

Important Note: Do not fill any Plastic Big Mouth Bubbler® fermenters with very hot liquid - temp should not exceed 140 degrees Farenheit (60 celcius)

BIG MOUTH BUBBLER® Product Specifications:
Capacity:5 gallon6.5 gallon
Height (w/lid, closed):22"23"
Fermentor Material:PETPET

Note: We recommend a soft cloth for cleaning the inside. Standard carboy brushes will scratch plastic fermenters leaving places for grime to hide. A warm cleaning solution will suffice. Do not use hot water on plastic fermenters of any sort. The Big Mouth Bubbler® is compatible with a standard carboy dryer when the dryer is used inverted.

*Pro Tip: Save your box and use it as a cover for your fermenter!

6.5 Gallon fermenters are perfect for the primary stage of beer or wine fermentation. The extra head space allows for the production of krausen on a 5 gallon batch of beer. Also available as a 5-gallon secondary fermentor.
3.5 / 5.0
168 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Stars
The lid sucks!!! Don’t buy it.
The fermenter itself is fine. The lid sucks!!! I can’t keep it on. If the silicon rings are wet at all it slips up on its own. I put the lid on put the airlock in placed it in the fermenting chamber and came back an hour to check the temp. The lid was completely up and not sealing anything. Pushed it back down every hour. It keeps creeping back up. I did this 4 times. Not impressed by this design at all. Go back to the old style. Overall don’t buy it.
Lid keeps creeping up and off
2nd carboy dame thing: lid is slipping up and off
April 11, 2018
2 weeks ago
Lid sucks!!! Don’t buy!! Hopefully it didn’t ruin my batch of beer
April 2, 2018
1 month ago
Excellent for primary fermentation as has plenty of space for yeast foam on top of 5 gallon batch.
March 27, 2018
4 months ago
...the lid man
If not for the lid, i'd like it. I don't even know that I'll use this as a backup.
I MAY use this as a secondary for this IPA i'm tryin, simply because I'm going to secondary this one, and i'd like something clear, and i no longer have my 5gal glass carboy.
Honestly, me having to gorilla tape the lid down during fermentation should've merited a refund. I even used 2 blowoffs! Dual plug top, extra hole to fill from thermowell plug...Still the lid lifted off.
I'd probably 3-4 star it, if not for the lid issue.
Personally, I'd avoid this like the plague until they revise the lid and just stick to buckets, or get a Spiedel, or go stainless.
This thing, however, is not worth the dollar.
March 11, 2018
2 months ago
Awesome Fermentation vessel
My first use of a wide mouth fermenter was the Fermonster, we have 3. They have a serious defect, much worse than the lid issues people gripe about on the BMB. The Fermonster is smooth walled, not reinforced and flexes like mad. This can cause airlock liquid to get sucked in when it expands again. You need to use a carboy carrier, or fingertip hold from the base of the lid area to prevent flexing. Also, the lid can crack if overtightened on the top perimeter. So varied limitations and drawbacks with the Fermonster.

In contrast the BMB (Big Mouth Bubbler) has great rigidity. OK, the lid has a tendency to creep up. I dinged it 1 star because of that. The advantages greatly outweigh that issue. Cleaning is incredibly easy. Also, when sanitizing the Star San bubbles easily pour out when left upside down as opposed to a narrow neck carboy. Then the weight savings vs glass. I have 2 BMBs and a depth charge. Today I am ordering 2 5g BMBs for secondary usage.

Wide mouth carboys are the greatest modern evolution for homebrews and the BMB has the best rigidity and a great line of accessories. Anyways any homebrewer is watching the start of the ferment and you adjust the lid (push and rotate) as needed.
March 11, 2018
7 months ago
These caps do not seal under pressure as others might state. JUST USE TIE STRAPS! we work on motorcycles and have a pile of them and it was not a big deal.
sorry for the great quality
sorry for the great quality
February 3, 2018
3 months ago
Not good for primary, but works fine for secondary.
I would not recommend using this product for primary fermentation. The seal is not good even if you dry everything thoroughly before installing. It will have leakage during primary if you have a good healthy fermentation going. The hole for the blow off tubing is also just a hair too big for a standard 1" ID tube. There will be a small amount of leakage around here as well. In short these are fine to use for secondary where there is less off gassing of CO2, but I would not recommend using this product in primary. I make yeast starters, oxygenate wort with air stone and o2 bottle, and have a temp controlled ferm chamber. My primary is always very healthy and vigorous.
January 18, 2018
4 months ago
Horrible lid
I tried the recommendations listed in the reviews to no avail. Wet or Dry, the lid pops out of the mouth of the bubbler. I have to use tape to hold the lid down during fermentation... Kind of a joke!! HORRIBLE lid design. I will not buy anymore until there is a fix.

January 16, 2018
3 months ago
POS Do Not Buy
Read that this thing was a giant pile. Got it free with a promotion... It is truly a POS, and makes me very disappointed that NB would sell this thing. If I can't find a weight that will fit on the top, this thing's going into the garbage.
January 14, 2018
3 months ago
Good product, however........
I love the wide mouth on the fermenters; makes it really easy to clean. I also love the PET Plastic which makes the fermenters lighter and a little more durable than glass. However, the lids suck. I have had them blow off numerous times, even with a 1 inch blow-off tube in the top. Customer service told me to flip the rubber gasket so that the larger ribs are on top, which I did. The lid still pushes up from time to time. It does not make sense why they would get away from a screw on type lid! It is very frustrating when I spend 5 plus hours brewing my all-grain batch, paying very close attention to sanitation, only to have the friggin lid blow off 12 hours into fermentation. Bring back the screw on lid, PLEASE, and then these fermenters will be excellent!
January 8, 2018
Start typing your question and we'll check if it was already asked and answered. Learn More
Browse 17 questions Browse 17 questions and 39 answers
Are these Bubbler Plastic Fermenters BPA free?
A shopper on Nov 29, 2016
BEST ANSWER: I looked on my bubbler, as well as one that is still in a box, & couldn't find anything that says it is or it isn't. Sorry.
Is there a solution for the universal lid popping out during active fermentation? Would the normal screw on lid work better during active fermentation?
joseph n on Jun 26, 2016
BEST ANSWER: flip the gasket upside down. I brewed my first batch and had the same problem couldn't get a proper seal. saw on a forum if you flip the gasket upside down if seals fine. fermenting a bourbon barrel porter right now no problems with seal.
How do these hold up to cold crashing? Will they collapse or crack?
A N on Feb 26, 2016
BEST ANSWER: Cold crashing an IPA in one of these for a week at 38F, no issues at all yet
Does the Big Mout Bubbler have volume markings?
A shopper on Jun 20, 2017
Big Mouth Bubbler® - 6.5 Gallon Plastic Fermentor
Big Mouth Bubbler® - 6.5 Gallon Plastic Fermentor
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Big Mouth Bubbler Plastic - 5 Gallon
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Big Mouth Bubbler® EVO 2 - 5 Gallon Glass Fermentor
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Siphonless Big Mouth Bubbler® - Ported 5 Gallon Plastic Fermentor
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Siphonless Big Mouth Bubbler® - Ported 6.5 Gallon Plastic Fermentor
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Big Mouth Bubbler® - 5 Gallon Plastic Fermentor
BEST ANSWER: Yes, the Big Mouth Bubbler Plastic does have indentations as markings but does not have numbers 1 - 5 or .
You have to count them to determine at what level you are at.
Might be dumb question but this product comes with a lid yes?
B R on Dec 27, 2015
BEST ANSWER: Yes. Comes with a lid and threaded collar. If you haven't yet, you'll probably also want to pick up a drilled stopper to accommodate an air lock
I’ve broken two glass carboys in my day. How does this one get transported? Do I simply pick it up and lug it to my fermenting closet or do the make a carrying handle?
A shopper on Oct 29, 2017
BEST ANSWER: I pick them up by the collar that holds the lid on. Or tilt and get a hand underneath. They are much easier to move than glass carboy
Where can I get a threaded lit for this?
A shopper on Jan 1, 2018
BEST ANSWER: If anyone knows please give me the answer too. The pressure fit lid that came with it leaks. I will not buy another one.
Is there a threaded lid for this? Not the included blue push in cap, but an actual screw on style cap? If not, can you tell me what size cap (like a mayo jar lid style) to get that fits the threads on the outside of the bubbler?
A shopper on Dec 27, 2017
BEST ANSWER: I purchased my 6.5 gallon fermentor in 2015. It came with a two-part lid, consisting of a lipped and recessed panel and a threaded ring. The panel is different from the lid currently shown on the product website - it does not have the silicone gaskets on the sides, just a single gasket to engage the lip of the fermentor. The threaded ring fits over the top of the panel and screws down on the fermentor threads. It does not appear that this lid is offered currently, but I'm not sure why the threads are still there.
what is the hottest this carboy can get before damage occurs?
T H on Aug 2, 2016
BEST ANSWER: Temperatures over 140 F will damage these plastic fermenters, so care must be taken when cleaning them or using them. We do not recommend pouring hot wort into them in any situation. - Mike W, Northern Brewer
Does this come with the universal lid or the standard lid? Also, are people having issues with universal lid popping off on the plastic big mouths like people have observed happening in the glass versions?
J A on Jun 26, 2016

Thank you for your question. This does indeed come with the new universal lid. Anytime you have very active fermentation you can run the chance of the lid and/or bung popping out.

Will the Brew Hauler work with these? I know there is a special harness for the BMBs, but I already have several Brew Haulers and would like to avoid buying yet another carry strap... Thanks!
J K on Apr 22, 2016
BEST ANSWER: The brew hauler will work on a BMB plastic. Not as well, but well enough to avoid getting a new strap! Cheers!
I never seem to get any bubbles from my airlocks. They are always seated tighly yet still no bubbles. Must be a leak in the lid. Is there supposed to be a gasket?
R E on Jan 14, 2016
BEST ANSWER: No gasket - I've personally never had an issue with there being no bubbles. My question would be if you checked the seal before putting any wort in? I did this by putting the lid on tight, putting my blowoff hose in and trying to suck air in...I was not successful! That told me certainly enough that it had a good seal. Hope this helps.
I was told not to use plastic when brewing mead due to bacteria, is this a legit problem?
P F on Dec 23, 2015
BEST ANSWER: Plastic fermentors are suitable for any fermentation including mead. Bacteria is not a problem provided that you clean and sanitize properly and do not scratch the plastic.
A shopper on Feb 5, 2017
BEST ANSWER: It helps to settle the yeast around the perimiter of the fermenter. I will try to siphon off the top of the bubble to keep yeast to a minimum
I have a standard NB blow off tube for a standard 6.5 gallon glass Carboy. Will this fit into the opening of the lid provided?
F R on Sep 21, 2016
BEST ANSWER: Yes, the whole dimensions are the same size in this lid as they are for the standard carboys.
I have read leaving beer in secondary for a long time in plastic can be harmful. is that still the case or have these new products gotten better?
N A on Mar 24, 2016
BEST ANSWER: The main reason to use glass for secondary is that plastic vessels don't always seal quite as well as glass, and oxygen can leak in and cause staling. Of course this isn't a problem during primary fermentation, but if you're going to do a secondary, especially a long one, glass is still usually better. Using plastic raises the risk a little, but it doesn't necessarily ruin it. That said, I've used plastic for a secondary before, and I've never experienced anything negative myself.
I have the big mouth bubbler with the dual port lid and a blow off tube. I really like the whole system but I have not used the blow off tube yet because it does not give a snug fit into the dual port lid. What is the trick to get a good fit, I just don't feel comfortable with the way it fits now.
Noel J on Nov 1, 2015
BEST ANSWER: Thanks for contacting us. Tricks include having the right angle for the tube so that it is pulled by the free end to make a seal at an angle- that is how most common set ups allow for it to seal. You can also try using some teflon tape of some sort to help get it snug. The tubing will vary based on kinks temperatures and many factors. You can try putting one end in hot water and then stretching the tubing over the lid port to stretch it and then it may fit more snugly inside the tube. Since it is there to allow yeas to leave as needed and fermentation is pushing everything away nothing can get in anyway and the tubing just prevents big messes and makes cleaning up easier.

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