Fermonster Carboy - 3 gal.

Fermonster Carboy - 3 gal.

Accessories for your Fermonster  
In Stock
60 day no hassle return policy. Details

The Fermonster is a brand new fermenter designed specifically for fermentation. MoreBeer! gave product feedback for over 2 years of development and we think they nailed the design. The large lid allows for easy filling and makes hop or oak additions a breeze. The smooth sides are fantastic for sanitization - no ribs or texture to collect yeast or bacteria. The punted bottom allows sediment to collect to the sides so that you can siphon liquid from the center.  Because they are made from virgin PET plastic they nearly unbreakable and a lot safer than similar glass carboys. Also notice the conical top which reduces surface area if you plan to store beer or wine long term.  

Made from heavy PET plastic, the same material used in 2 L soda bottles, which is nearly impermeable to oxygen penetration.  Due to the thickness of the material and the overall geometry the Fermonster does not require ribs or dimples for stability.  That results in a super smooth interior surface that reduces yeast and sediment buildup making it the easiest to clean, most sanitary PET carboy on the market.  The huge 4" opening makes filling a breeze, and cleanup is as easy as wiping down the inside.

These fermentors are completely air-tight and the lids sealed tight with an O-Ring.  Additional O-Rings and Lids both with and without holes are available for purchase, see our You Might Also Need items below.


  • 4" inner diameter wide mouth carboy - easy to clean!
  • Food grade PET plastic construction is nearly impermeable to oxygen penetration
  • No hard to clean dimples or ribs
  • Punted bottom
  • O-Ring and Lid with one hole is included (Fits #10 Stopper)
  • Additional O-Rings and Lids available
  • Weight: 1.5 lbs
  • Temperature Limit: 140° F
  • Height: 14.6 inches
  • Diameter: 9 inches
  • Completely taste and odor free
  • Perfect for Beer, Wine, Cider, Mead, Kombucha or any other fermented beverage!

Please note: the pictured #10 Stopper (FE470VS) and three piece airlock (FE370) are not included.

Item # FE258
Shipping Eligible for Free Shipping Program
Availability California - In Stock
Pennsylvania - Out Of Stock
Weight 2 LBS
Community Q&A

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Browse 6 questions Browse 6 questions and 51 answers
Why did you choose this?
MoreFlavor Store
Smaller baches
Xavier E on Jul 2, 2020
Wide mouth for easy dry hopping
William W on May 27, 2020
Smaller baches
Xavier E on Jul 2, 2020
Small batch testing
sean r on Jun 13, 2020
Wide mouth for easy dry hopping
William W on May 27, 2020
Step up from 1 gal
August R on May 16, 2020
Have used FerMonster before. Works well in my experience
Mike W on Apr 19, 2020
Perfect for brewing mead
Valued C on Apr 14, 2020
it works for pickled tourist display in our museum
David H on Jan 23, 2020
Use for small batch beers. Currently using for aging specialty stouts/porters.
Paul S on Oct 25, 2019
Small-batch (2.5 gal) brew
Michael B on Oct 3, 2019
to ferment 2 gallon melomels
John D on Sep 6, 2019
Size I use often. Wide mouth.
Larry L on Aug 31, 2019
I am a first time wine maker and wanted to something smaller than a glass carboy.
Kristiani s on Aug 28, 2019
doing 2.5G batches now. ditching the glass carboys!!!
George M on Aug 28, 2019
I like have a 3 Gallon fermenting option.
Keith B on Aug 28, 2019
Perfect size for small Cider and Mead batches
Ethan C on Jul 19, 2019
Split batches and small batch brewing
Isaac Ramsey on Jun 21, 2019
Use for smaller batches and top off.
Sammy K on May 25, 2019
Small batch fermentation
Frederick B D on Apr 20, 2019
I want to do small batches of sour beer.
Steven H on Apr 4, 2019
want to move up from 1 gal, but not 5 gal yet
Michael H on Jan 19, 2019
Perfect size for starting out.
Keith G on Jan 17, 2019
My son persuaded me to brew in smaller batches.
John M on Jan 16, 2019
to split a 5 gallon batch into two separate fermentations
Cody S on Dec 27, 2018
Large mouth opening
Dwane C on Nov 21, 2018
Easy clean-up. Using for smaller batches of mead
Allan M on Nov 19, 2018
To make a small batch.
Lisa Ferguson on Nov 17, 2018
For 2.5 gallon lager batches in mini fridge
Barrett L on Sep 24, 2018
Small batches
Jason W on Sep 13, 2018
right size. Big opening. Good price.
Charles M K on Sep 10, 2018
I don’t want a 5 gallon since I don’t have a lot of space and my 1 gallon just isn’t enough.
Inome W. C on Aug 24, 2018
Ease of cleaning and a great price!!
Jeffrey Mauriello on Aug 13, 2018
John O on Aug 10, 2018
For a friend
Blackmon on Aug 9, 2018
A great design, for easy cleaning, and a good size for easy fermentation temperature control in a igloo cooler water bath
Dan Kuczmarski on Aug 9, 2018
Wide mouth and fits in my fermentation chamber.
Bernard W on Aug 8, 2018
Small batch brewing
Todd Z on Aug 8, 2018
To do split batches
Justin W Thomas on Aug 4, 2018
Wanted something small enough to use with Zymatic batches and the BrewJacket temperature controller. This should fill the bill.
Michael S on Jul 31, 2018
Lighter, less likely to break, easy to clean, cost less than glass
Steven McPeak on Jul 23, 2018
want to do split batches
Daniel B on Jun 12, 2018
Russell L on Jun 6, 2018
for making wine
Jim VanCise on May 24, 2018
Want to make a small batch of wine
Charles Stahl on May 5, 2018
I'm currently making a lot of 3 to 3.5 gallon batches
Dustin P on Apr 13, 2018
Small batch testing
sean r on Jun 13, 2020
Step up from 1 gal
August R on May 16, 2020
On the larger versions, the line near the top where the sides begin to slope indicates there is one gallon of space left. Is that true for the 3-gallon version as well?
Douglas Frazer on Aug 17, 2018
Any plans to offer this size with a spigot?
Tom Meskill on Jun 8, 2018
BEST ANSWER: We are always looking for new solutions and products. No confirmation if this will be manufactured with a spigot, but it's not out of the question. You could attempt drilling the plastic yourself.
Can the 3 gallon Fermonster be used to ferment a 2.5 gallon batch?
Warren Parker on Sep 13, 2018
BEST ANSWER: Hi Warren - Should be okay, ferm caps couldn't hurt either.
Foam Control (FermCap S) (1 oz)
Foam Control (FermCap S) (1 oz)
Any plans on future versions to increase the thickness of the walls? I own this, and love it, but fear for it's longevity
Brian Fredlund on Jan 16, 2019
BEST ANSWER: Hi Brian - Unfortunately we do not know of any future versions of the fermonster that will have thicker walls. Apologies.
Are the side walls thick? I purchased a 1 gallon version and am disappointed on how thin the side walls are compared to my 6 gallon Fermonsters.
Justin W Thomas on Jul 20, 2018
BEST ANSWER: Hello Justin - The side walls of FE258 and not quite as thick this as those on FE250.

3.8 / 5.0
16 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Wide Mouth, Screw top w/seal
Great for small batches, test batches or if you are just getting started. Easy to clean & dry hop plus its harder to break than glass. Top does take a large than average plug (#10 is needed)
May 5, 2020
2 months ago
Great upgrade from a 1 gallon carbon. Easy to use and prep. Have a gallon brewing now, hopefully easy to clean as well as prep for brewing
April 11, 2020
3 months ago
Great for cleaning, bung hole and o-ring needs improvement
Picked up two of these 3-gallon fermonster plastic carboys. The wide-mouth opening is great for cleaning -- easy to reach in and scrub down with a soft cloth. Also, very few internal ridges for grime to hide. The lids really solid and easy to remove.

Wish the bung hole was a standard size. Feels unnecessarily large, and requires #10 stopper which never feels quite tight to the lid. The thin o-ring that seals the lid to the carboy is also very finicky. I had a lot of trouble getting it to fit in the tiny groove in the lid. Very difficult to remove for proper cleaning.
May 8, 2019
1 year ago
Response from MoreFlavor
Thank you so much for your feedback. We really appreciate the honesty and value great feedback like this as it helps us improve our products. Cheers!
May 9, 2019
Tyler W Staff
Easy to clean. Light weight.
April 18, 2019
1 year ago
very flawed lid
I do not believe this lid went thru any kind of testing, prior to selling to home brew people. It is impossible to screw lid on and have it stay in place. if empty and turn upside down you may get lucky enough to keep gasket in place. try that with a gallon brew inside. in the upright position you can not screw lid on with out gasket falling out, it will not seal. a simple design change of lid to secure gasket in place would make these a good purchase. as they are now, not good.
January 29, 2019
1 year ago
Response from MoreFlavor
Hey so sorry about your experience. We try very hard to create the best experience for our customers and provide quality products. Please give us a call at 1-800-600-0033 or email us at info@moreflavor.com so that we can assist you. We are here to help. Cheers!
January 30, 2019
Tyler W Staff
Liking all my fermonsters so far, and the 3 gal is a convenient size.
November 18, 2018
1 year ago
works as designed
Bought this so I can do small batches of fruit wine. The only thing I didn't like was how thin the walls are.
November 17, 2018
1 year ago
The material of the 3 gallon fermonster are thin, thin, thin. Did I mention very thin? I don't expect this to last after it's first somewhat hard bump.
October 2, 2018
1 year ago
Response from MoreFlavor
Hey so sorry about your experience. Thank you so much for your feedback. We really appreciate the honesty and value great feedback like this as it helps us improve our products. We try very hard to create the best experience for our customers and provide quality products. Please give us a call at 1-800-600-0033 or email us at info@moreflavor.com so that we can assist you. We are here to help. Cheers!
May 29, 2020
Malcolm MB
Initially a problem developed but morebeer helped out
Pitched the yeast and never any bubbles in the airlock. But there was a thick Krause which indicates it was fermenting. Finished, bottled, and then put water in the fermonster and it leaked. Retightened several times and couldn’t get it to stop. Not leaking in the gasket but rather around the lid to airlock area. Called morebeer and they said make sure totally dry and try agin so I did to no avail. Called again asking if they had any other #10 stoppers other than the one they originally recommended. Morebeer recommended the universal stopper #10 with hole cost a little more 3.60. This was the answer and I am quite pleased since this is light, a good size for experimental batches, and love the wide mouth. Thank you morebeer.
September 25, 2018
1 year ago
Great concept but compromised by making the walls so thin.
This fermenter works very well for primary fermentation of 3 gallon batches. The large neck opening enables easy cleanup. The one shortcoming of this vessel is that the wall thickness is thin compared to the 3 gallon narrow neck vessels and the 7 gallon Fermonster from the same manufacturer. Had I known in advance these were manufactured with thinner walls, i would have stayed with the narrow neck version. If the manufacturer made with thicker walls it would be a five star product
September 23, 2018
1 year ago