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Fermonster Carboy - 3 gal.

Fermonster Carboy - 3 gal.

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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 vigin 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 - In Stock
Weight 2LBS
Community Q&A

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Browse 5 questions Browse 5 questions and 27 answers
Why did you choose this?
MoreFlavor Store
Large mouth opening
Dwane C on Nov 21, 2018
To make a small batch.
Lisa F on Nov 17, 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 F 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!!
Valued C 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
J I 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
Easy clean-up. Using for smaller batches of mead
Allan M on Nov 19, 2018
For 2.5 gallon lager batches in mini fridge
Barrett L on Sep 24, 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)
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.
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

3.8 / 5.0
11 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Liking all my fermonsters so far, and the 3 gal is a convenient size.
November 18, 2018
2 months 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 month 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
2 months ago
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
3 months 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
3 months ago
Price is great, and I needed this size. Downsides are walls are a bit thin/weak, and o-ring in lid can be quite difficult to sit in groove properly.
September 6, 2018
3 months ago
Big is Not Always Better
I’m 76 . I’ve been growing cold hearty grapes for wine since I was for 40 years . Blending varieties is a truly learning experience. Make3 gallons of wine from one variety not only teaches you the true characteristics of that grape ( Should one use it as a wine by itself or what would it add to a blend . ) . The small experimental vintner like I am does have the options of a professional business. They would think my 1 .5 acres of grapes a joke . I find this carboy a blessing. When you are my age lifting glass is tough. This is truly helpful . Wish my small finances aloud me to purchase more . One takes one year at a time .
August 26, 2018
3 months ago
OK Fermenter, could be more robust.
I love the 6 gallon versions. Good thick plastic. The 1 gallon version I have bought recently is very very thin. I was hoping the 3 gallons would be thick like their big brothers, but they are made of the same thin plastic as the one gallon versions. Disappointed.

I can easily see putting creases in the side walls, if you have to crank down on the lid to get it unscrewed. The Fermonster is known for having "too good" of a seal if you crank down on the lid (not recommended). This is one reason why they also sell a wrench for the lids, which I also have.

I bought these to replace the narrow neck Better Bottles I used for years. If the plastic was as thick as the 6 gallon versions, this would easily get 5 stars.
August 18, 2018
4 months ago
great fermenting containers
I like these Fermonsters because I can get my hand inside to clean it. Ordering and delivery from MoreBeer were quick and easy. I have a couple 5-gal Fermonsters that I used to make hard cider. This time I bought a couple 3-gal (and a 1-gal one) to make mead. The only down side, if you want to call it that, is it takes a lot of honey to make a 3-gal batch of mead. But my bees have been busy, the yeast is now busy in the Fermonsters, and soon I will be busy sipping the results.
August 6, 2018
4 months ago
I do like these carboys
This is a great size for doing batches of wine and mead. The wide mouth makes dealing with fruit in bags easy. Using all the different size Fermonster carboys are great way to brew and make wine. Lighter, safer, easy to clean and cost less than glass. The lids are interchangeable between carboy sizes too.
August 5, 2018
4 months ago