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Erlenmeyer Flask - 5000 mL
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Our HUGE 5000ml Erlenmyer Flask is 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. Large populations of active yeast help ensure flavorful beer free of off flavors. Because it 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 2LBS
Community Q&A

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Why did you choose this?
MoreFlavor Store
For yeast starters
Jason C on Feb 12, 2018
10 gallon lager and high gravity starters
Jason S on Jan 30, 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
sold my 2,000 ml flask
CPT Krug, Jonathan, G on Feb 12, 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
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
53 Reviews
5 Stars
4 Stars
3 Stars
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1 Stars
Good product
Great flask. Makes it easy to create appropriate sized starters for 10 gallon brews
February 4, 2018
1 month ago
Good product
Great for a starter on a 10 gallon fest lager
February 3, 2018
1 month ago
Thicker glass than anticipated
I use this flask to make > 2 liter yeast starters for beer brewing. It works as intended. I was pleasantly surprised that the glass is relatively thick compared to other Erlenmeyer flask I have used.
January 24, 2018
1 month ago
Works as intended. It did have some small scratches and scuffs but It doesn't effect the product.
January 23, 2018
1 month ago
Great quality!
Very high quality flask! Much thicker glass than most 5000ml flasks I have used and broke!! I also purchased 2 of the 3000ml flasks from MoreBeer and they are the same high quality thick units!
September 7, 2017
Got it quick! Really needed a bigger flask for bigger brews. Read a lot about people saying the stir bar wouldn't stay, so I immediately filled it with water and I have no problems with mine. Great looking flask and I'll have a starter in it this weekend!
September 8, 2016
Well built, nice flask but one major issue with the one I received: the magnetic stir bar will not, even at low revs, hold in the center. I use a 2" bar in a flask this size as the 1" does not have enough "juice" and it keeps getting thrown to the side. I tried several different bars and even the smaller one to see if I could get it to hold but to no avail. I put 3000 ml of water in the flask so I could hopefully see the problem and I think the bottom is crowned or convex so the magnet tends to drift to the side, thus causing the problem. Oh well, back to shopping for another flask.
July 18, 2016
Concave Bottom renders useless.
The bottom of the flask is concave and not flat. This prevents a stir bar from staying put, essentially getting thrown to the edges of the flask at all but the lowest speeds. Therefore it is essentially useless for its intended purpose.
April 14, 2016
Glad I got a 5L over another 2L
I can still make a 2L starter in this flask, but when I need a bigger starter for a larger batch or for a lager, I'm glad I can make it in one flask.
May 28, 2015
A must have for big beers or 10 gallon batches
The easiest and safest way to make a starter is with borosilicate glass. I have 2 of these 5L flasks because 1 just wasn't enough.
May 27, 2015