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!

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

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Browse 4 questions Browse 4 questions and 61 answers
Why did you choose this?
MoreFlavor Store
high gravity lager starters
Andrew L on Oct 15, 2019
Big yeast starter
Walter M on Aug 31, 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 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
Nice and big
Royce D W on Mar 21, 2019
My other flask is for smaller batches
Eric P on Feb 26, 2019
Jeremy H on Feb 1, 2019
Lager and 10 Gallon batch starters
Craig Z on Jan 24, 2019
Jack M on Jan 22, 2019
To step up starters for high gravity beer.
Darren A on Jan 22, 2019
10+ gallons starters
Avery Colomb on Jan 21, 2019
Need to make big starters.
Alex C on Jan 11, 2019
5 liter is the size you will need to make starters for 10 gallon batches
Valued C on Dec 24, 2018
Cause I wanted it
Carton Brewing Co on Dec 15, 2018
Great for 10gal starters
Jeff A on Nov 25, 2018
Bigger starters
john breithaupt on Nov 24, 2018
Jeanine A on Nov 24, 2018
jason s on Nov 17, 2018
Great Price
Mark E. W on Nov 17, 2018
To make lager starters
Eric Hansen on Nov 17, 2018
I had one that worked great, but knocked it off a high shelf. This time I'm getting two!
Eric B on Oct 26, 2018
For large yeast starters
JOHN DUNLOP on Oct 5, 2018
to make yeast starter
Garry W on Aug 28, 2018
Need to make my yeast stronger!
Jon S on Jul 19, 2018
Time to put on my big boy pants and make the right starters
karl h on Jul 11, 2018
Over build yeast starters
Joshua T Vann on Jul 5, 2018
large yeast starter needed
Craig Isvak Managing M on May 28, 2018
Yeast starter for lagers.
Dennis Ellis on May 15, 2018
I want to make single, over-sized starters and save 1/2 for next time
Art Blackwood on May 15, 2018
I picked these items to present science experiments at schools across America. I am The Science Machine! Google me...
Michael G on May 7, 2018
big batch yeast starters
Kevin L M on Apr 12, 2018
To make larger starters
Joseph K on Apr 11, 2018
I already own a 2000mL flask and I need the larger size because I'm going to be doing larger yeast starters
James P on Mar 31, 2018
needed large flask for starters
Stephen Tyner on Mar 21, 2018
To make larger starters for 10 gal batches.
John Richardson on Mar 20, 2018
Brad M on Mar 16, 2018
it's a handy size for starters
Ed M on Mar 16, 2018
I will use this to make yeast starters for 10 gal. batches.
John B on Mar 16, 2018
I nee larger starters
Robert P on Mar 6, 2018
I needed a flask for larger starters.
Nick B on Mar 1, 2018
price, free shipping
Scott N on Mar 1, 2018
Good price
Clayton B on Sep 9, 2019
Yeast starters
Patrick M on Aug 28, 2019
What is the diameter of the bottom of this 5000 mL erlenmeyer flask?
Dennis Ellis on Jan 30, 2018

The flat part of the bottom is 6.5 inches in diameter. The widest dimension is 8.75 inches.
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 Woite 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
73 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
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
6 months ago
Great flask
Haven't had any issues using it stove top (electric). Recommended!
April 7, 2019
6 months ago
This is the largest flask I have ever seen! I filled it up to the 2L mark for my starter. Works on a stir plate and I'm not sure why so many people complained about the bottom. Mine starter stirred just fine. They pack this thing so well it's probably rare that it gets broken upon arrival.
February 25, 2019
8 months 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!
February 26, 2019
Tyler W Staff
Great flask for the price.
Great flask for the price. I had a little trouble getting the stir bar to stay put. Ended up putting a plastic dinner plate on the stir plate; the increased height and/or extra plastic calmed things down. Made a healthy whirpool from 2L up to 4L, no problem, using 2in bar.
January 26, 2019
9 months ago
Good flask, good deal
Everyone who brews 10+ gallon batches should own a 5L flask unless they want to buy a ton of yeast for each batch. I do not boil directly in mine. I recommend using it with a foam stopper for gas exchange and a couple drops of Fermcap to keep rowdy yeast in check. The bottom glass is slightly uneven so it can be finicky to get my stir bar going smoothly but that's to be expected with glassware of this grade. No complaints.
January 9, 2019
10 months 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!
January 10, 2019
Tyler W Staff
Not Wide Mouth
Excellent quality great price. However not wide mouth, makes pouring wort/yeast into it difficult. Flat bottom, works great for spinning magnets.
January 8, 2019
10 months ago
Would recommend this product. 5000ml Erlenmeyer flask.
Good thick glass, perfect for my needs.
December 29, 2018
10 months ago
Works good
Works good. Didn’t explode when I boiled on stove and cooled in ice bath :)
December 16, 2018
10 months ago
I had a 5000ml flask I got off Amazon and could never keep the stirr bar going. This flas I can run the bar at any speed with no problem. Did a 3l starter with 2 giga packs worked great
November 16, 2018
11 months ago
Good Glass!
Good quality glass! Makes an excellent starter!
Good quality Glass!
Good quality Glass!
October 17, 2018
1 year ago