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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 - Out Of Stock
Weight 7LBS
Community Q&A

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Browse 2 questions Browse 2 questions and 38 answers
Why did you choose this?
MoreFlavor Store
Great for 10gal starters
Jeff A on Nov 25, 2018
Jeanine A on Nov 24, 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 D 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 V 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 T 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
For yeast starters
Jason C on Feb 12, 2018
sold my 2,000 ml flask
CPT Krug, Jonathan, G on Feb 12, 2018
10 gallon lager and high gravity starters
Jason S on Jan 30, 2018
Have a looking to do very large starters so I thought this would be a good container to get
Matthew on Jan 29, 2018
to make starter for 10 gallon batches
Timothy M on Jan 10, 2018
Bigger starters
john breithaupt on Nov 24, 2018
jason s on Nov 17, 2018
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.

4.5 / 5.0
66 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
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
1 month ago
Good Glass!
Good quality glass! Makes an excellent starter!
Good quality Glass!
Good quality Glass!
October 17, 2018
2 months ago
5000ml flask
The flask worked great for a 2.5L starter for a lager.The bottom is nice and flat so there were no problems with the stir bar on my stir plate. It is advertised as Borosilicate and able to withstand going from very hot to cold but it does not have any markings, such as Pyrex. I tried the double boiler method as mentioned in the info but after 30+ minutes the wort was not boiling so I emptied the wort into a kettle, boiled, then into the sanitized flask.
September 27, 2018
2 months ago
Super quality!!
Excellent shipment, it arrived without a scratch, definitively the best size for my 1 bbl starters
August 29, 2018
3 months ago
Good 5L flask with a flat bottom.
Great 5L flask. This one has a very flat bottom so it still works with smaller stir plates such as the stir starter (what I have).
July 21, 2018
6 months ago
not sure what grade this is
my flasks came with scratches, bubbles and chips not sure I would put these on a flame and waste the yeast if it exploded. I will be sending these back. They don't even say that they're pyrex. No wonder they recommend the double boiler method these flasks are wonky at best
June 11, 2018
6 months ago
Works with my stir plate
No issues with my stir plate. Stir bar holds tight in center of this flask at all speeds even though the bottom is slightly concave. A high quality stir plate with strong magnets may over come the drawback of a concave bottom. The graduation markings are "approximate." This isn't an issue for me because I use measuring vessels that are more accurate as a work around. This flask is priced appropriately for what you get, which is why I purchased it. My equipment was able to overcome the slight flaws easily, which made this flask usable for me and a bargain.
June 8, 2018
6 months ago
Response from MoreFlavor
Great review!
June 12, 2018
Zach R Staff
Perfect for harvesting yeast
April 30, 2018
8 months ago
Love it for lager starters
April 16, 2018
8 months ago
Inaccurate volume markings
The two 5L flasks I received were not Bomex flasks and the volume markings are way off. We’re paying $40 for these and they’re not even graduated correctly!
April 16, 2018