Erlenmeyer Flask - 5000 mL

Erlenmeyer Flask - 5000 mL

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This Erlenmyer flask is huge, coming in at 5000 ml (5L!), making it the ideal vessel to make a large yeast starter for a 10+ gallon batch. The best brewers make large yeast starters to get their beer fermenting fast, and most of them do so in an Erlenmeyer flask. Large populations of active yeast help ensure flavorful beer free of off flavors. Because this flask is made from borosilicate glass you can move it from a boil into a cold water bath for cooling. This means you can do the whole process in one container, keeping it simple and helping to reduce the risk of contamination when transferring from one container to another.

Double Boiler Method
It is important for your safety to heat water in the flask with a heat source that distributes heat evenly. Morebeer! recommends using the "double boiler method." This process involves using a boiling water bath on the outside of the flask to heat up the water inside the flask. All you need is a kettle 3 gallons or larger. This process is much safer and efficient. If the flask should break or boil over, your kettle will be there to collect the contents, thus keeping your stove clean and keeping you safe.

Safety First: Please take us up on a great deal - save $14.95 when you purchase a 5000ml flask and our BE300 5 gallon stainless steel kettle at the same time. Use Promo code SAFETY1 at checkout.


  • Massive 5L (5000ML) Capacity
  • Made from Borosilicate Glass (also known as Pyrex)
  • Fantastic price for a flask of this size
  • Produced for MoreBeer!

Why make a yeast starter? (from our FAQ)
We build starters for 3 main reasons. First, to ensure yeast health. By making a starter 1-3 days in advance, you ensure that your yeast is healthy and strong and ready to do its job. Second, to create more yeast. By making the starter you will increase the cell count of the yeast, giving you a better chance of keeping bacteria's and wild yeasts from fermenting your wort. Third, if you are making high gravity beers. If you are making a high gravity beer (1.060+) you will need more yeast to start the ferment faster. High gravity beers will also finish more completely when you pitch ample quantities of yeast.

In the lab world, these flasks are known as "Student Grade". Student grade flasks may have small scratches and air bubbles. A great flask for making yeast starters!

Kegland Part Number: KL04008

Item # Y450
Shipping Eligible for Free Shipping Program
Availability California - In Stock
Pennsylvania - In Stock
Weight 7 LBS
Community Q&A

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Browse 4 questions Browse 4 questions and 63 answers
Why did you choose this?
MoreFlavor Store
For starting yeast
Harold N on Nov 19, 2020
For lager starter
Jason R on Oct 29, 2020
For starting yeast
Harold N on Nov 19, 2020
need back up
Michael W on Nov 6, 2020
For lager starter
Jason R on Oct 29, 2020
Excellent price
Michael on Sep 30, 2020
Good reviews and best price
Brant B on Sep 23, 2020
Yeast starter for 10+ gallon batches
Curtis B on Sep 22, 2020
Gianmarco L on Sep 3, 2020
Need something bigger than my 2L for 10 gal batches
Michael A on Aug 27, 2020
it was a gift request
Lisa T on Aug 18, 2020
For making starters for my 15 gallon batches
Valued C on Aug 4, 2020
Need a bigger flask for high gravity starters
SCOTT S. on Jul 16, 2020
right size, right price
Ken M on Jul 8, 2020
LAGER starter
Pete T on Jul 3, 2020
to save on yeast cost
Michael Dean on Jul 3, 2020
I like big flasks...
Philip B on Jun 16, 2020
yeast starters
Daniel W on Jun 12, 2020
For brewing beer
Heather B on Jun 10, 2020
Yeast starters for 40 liters of lager
David Carpenter on Jun 5, 2020
for making larger starers
Will S on May 23, 2020
If you make 2L starters, you're gonna boil over with anything smaller. Just buy it and you'll be happy.
Adam L on Apr 19, 2020
Make massive starters
Allen S on Mar 26, 2020
good price
Marco a L on Feb 25, 2020
Yeast cultures for 3bbl brews
Douglas B on Feb 22, 2020
big starters
Charles W on Feb 20, 2020
Ryan A on Feb 6, 2020
Upgrading starter equipment
Mark A on Feb 4, 2020
Fairest price around by far!
Dwain R W on Jan 29, 2020
1431 Pine S on Jan 23, 2020
Want to make yeast starters
Jim B on Jan 14, 2020
Online recommendations
Jaime L on Dec 5, 2019
large yeast starters
Brandon W on Dec 2, 2019
Need a larger flask for 10 Gallon batches and lagers
Nelson L on Dec 2, 2019
Steven C on Nov 30, 2019
Great price
Steve K on Nov 30, 2019
Yeast starter for 10 gallon batches
derek barrington on Nov 25, 2019
Mike on Nov 18, 2019
Recommended by a friend
David S on Oct 24, 2019
high gravity lager starters
Andrew L on Oct 15, 2019
Good price
Clayton B on Sep 9, 2019
Big yeast starter
Walter M on Aug 31, 2019
Yeast starters
Patrick B M on Aug 28, 2019
I have a 1 bbl system.
Chris G on Jul 29, 2019
for yeast starter
Norm B on Jul 23, 2019
Yeast starters
Kyle C on Jul 20, 2019
Head space for 1.5I yeast starters
Blair b on May 27, 2019
Need larger flask/yeaster starter but still fit on stir plate.
Michael W on Apr 25, 2019
Large lager starters, and to be able to over build ale starters to save money on yeast.
adam w on Apr 14, 2019
I use 5L erlenmeyer flask to create starters for large volume high gravity batches
John R on Apr 9, 2019
I want to make a yeast starter with plenty of air space.
Malachi B on Apr 5, 2019
Large starters for 12 gallon batches
Andrew J. G on Mar 23, 2019
need back up
Michael W on Nov 6, 2020
Excellent price
Michael on Sep 30, 2020
What is the diameter of the bottom of this 5000 mL erlenmeyer flask?
Dennis Ellis on Jan 30, 2018
BEST ANSWER: There may be a touch of variation unit to unit - my numbers differ slightly from Dennis'. On mine the flat part of base is 5+7/8" around the raised flat lip. Widest part is 9". Height is 15".

The volumetric markings on mine are not as close as I would like (probably off by ~ 1/4L or so @3L), so I use a digital scale to measure the added liquid (1kg ~= 1L water at roomish temp).

I don't trust direct heating any flask, especially this big over direct flame, so I never do that - I'd love to hear from others who have success doing this. But I have never had any issues transferring hot liquids into this flask - no cracks, etc. But I have been careful. 5L is a lot of potential pain - better safe than sorry. Cheers!
Using Double Boil Method:... "This process is much safer and efficient. If the flask should break ..." Why would the flask break from boiling if its pyrex?
Austin Woitte on Aug 13, 2019
BEST ANSWER: Well, in a perfect world with perfect quality, you could ignore this advice, if you could be sure you never damage the flask in an undetectable way.... these flask are not to lab quality standards, they are essentially seconds...more prone to failure I suspect.... that said I boil direct, using the same flask at least 30 times so far
What size (replacement) foam stopper does this need? 11 1/2? Where do I get this?
Thomas Garten on Feb 18, 2019
BEST ANSWER: Hi Thomas - The #12 foam stopper should work perfectly with the item. Unfortunately, we do not have a specific recommendation for the purchase but a quick google search should bring satisfactory results.

4.6 / 5.0
81 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Excellent! And thank you to the customer service team for awesome service!!
September 30, 2020
2 months ago
Bigger is better!
The size of this thing is mammoth. It is just what you need to for yeast starters for high alcohol brews. It would have gotten 5 stars but there are bubbles in the glass in certain areas, which means I have to boil the malt in a pot before transferring the hot liquid to the flask. I don't want it to shatter. Small inconvenience in my mind.
September 17, 2020
2 months ago
Big Beer Needs Big Starter
This is the Mac Daddy Flask. Big beer plans need a big starter. A gallon on the stir plate makes it happen. Discounted 1 star for the graduation marks at 4 & 5 liters being off by quite a bit.
September 8, 2020
over 2 years ago
Good flask with bad volume markings
For the price, this is an excellent 5-liter flask, just the thing for huge yeast starters. Be warned, though, that the volume graduations are not accurate, at least not on my model. The 2,000 mL mark is spot on, but others are not. I wouldn't discourage potential buyers from getting one of these if you just need a big, affordable vessel to contain a starter, but know that you can't trust the graduations on the side. Use a scale and you'll be fine, though.
June 26, 2020
5 months ago
Great Product
I mean, it works great. When you want the flexibility to make starters of any size, just get a 5L.
April 29, 2020
7 months ago
Very useful and arrived as promised
December 23, 2019
1 year ago
Good value
Works as intended. Building up a starter right now. Great for 10 gallon batches
December 17, 2019
12 months ago
A good purchase
This arrived as advertised. A really big Erlenmeyer flask that seems to be very solid and well made, with uniformly thick walls and base. No scratches or defects found. Holds up to heating. And it came at a very good price for this size and quality of lab glassware.
November 7, 2019
1 year ago
Just what I needed
Great for starters! Now I don’t have to be concerned with my yeast starters bubbling over and making a mess. Cooked right on the stove and then direct to cool water and ice with the borosilicate. Still works with my little stir plate as well.
April 30, 2019
1 year ago
Great flask
Haven't had any issues using it stove top (electric). Recommended!
April 7, 2019
1 year ago