2000mL flask to 5000mL flask

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Konadog

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For the last 2 years I have made yeast starters in my 2000mL flask, and usually would overflow at high kräusen, loosing a lot of yeast.
Flash forward to this year and I have a new 5000mL flask. I have made 3 starters so far, and not one has show the activity, or high kräusen that I had in the 2000mL flask. I do seem to get the same amount of yeast, but not the foaming mess that I had before. Has anyone else noticed this?

I was making a 2000mL starter in each.

My thought is that I can create a bigger whirlpool in the 5000mL flask, in a much shallower liquid amount, possibly pulling down the kräusen before it can fill the flask, but I'm not sure.

The yeast's I have used this year so far are WLP001, WLP090, and WLP051.
 

BGHSmt7

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Another aspect to think about is the narrow diameter of the 2L vs the 5L flask. Think of it as primary fermentation of 5 gallons of wort in a 5 gallon carboy vs a 6.5 gallon carboy. More headspace for it to have fun in :D
 

The_Bishop

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I quit using narrow mouth flasks for starters. I've been using wide mouth Erlenmeyer flasks because they're not so prone to volcanic eruptions and far easier to clean.

I just use a small sanitized plate over the top when on the stirplate.
 
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I have seen a similar affect. The geometry of the 2000ml flask means there is very little volume for head space.

Conversely, the 5000ml flask has tons of volume down at the liquid level that the krausen doesn't look very big.
 

Beer-lord

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I've shown a good deal of krausen in my 5L flask though I admit, proportionally, not the same. I never, ever worry about seeing anything. Use good yeast, keep things clean and let er rip!
 
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Konadog

Konadog

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I've always wondered why people refer to them as 2000ml and 5000ml and not 2L and 5L?
Normally I would, but once when I was talking about my 2L flask, and someone said I should get a larger one, a 2000mL :confused: I was just keeping it simple :)

Sounds like what I'm seeing is normal. I think it's that I have a better vortex in the 5L, and it's pulling everything back in before it stacks up.
 
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