Stupid Question

And the obvious answer i think would be Yes, But I want to double check

Will a 2000 ML Flask be able hold a full 2000 ML of starter and have a vortex with out the liquid over flowing?

Sorry, never took any Chemistry classes.

If the 2L mark is well below the lip then I would think the answer would be yes. Otherwise, no. And I'm not so sure that is chemistry related. More like Home Ec.

cheffriz said:

A 2000 ML Flask will be able hold a full 2000 ML of starter with a vortex fully displacing the liquid with out it over flowing?

Sorry, never took any Chemistry classes.

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I was with you up to the part about, "with a vortex fully displacing the liquid". Obviously, anything fully displacing the liquid in the flask will cause it to overflow. A vortex is neither desirable or necessary IMO. A gentle stirring action is all that is needed. Most 2 liter flasks will have considerable freeboard above the 2 liter mark, so yes you can fill them will a full 2 liters and still run them on a stir plate if that is what you are asking.

Catt22 said:

I was with you up to the part about, "with a vortex fully displacing the liquid". Obviously, anything fully displacing the liquid in the flask will cause it to overflow. A vortex is neither desirable or necessary IMO. A gentle stirring action is all that is needed. Most 2 liter flasks will have considerable freeboard above the 2 liter mark, so yes you can fill them will a full 2 liters and still run them on a stir plate if that is what you are asking.

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Probably the wrong phrasing, but with the stir plate operating a full speed it will not force the starter over the top of the flask, perhaps that makes more since.

However, I was under the impression, that the purpose of the stir plate was to aerate the starter as yeast is being propagated, therefor the need for the vortex. Please inform me if this is incorrect.

Wouldn't the krausen overflow if doing a full 2L in a 2L flask?

I kept mine under 1800 ML and there wasn't much krausen at all. I think the stirbar kept the foam down to a minimum.

cheffriz said:

Probably the wrong phrasing, but with the stir plate operating a full speed it will not force the starter over the top of the flask, perhaps that makes more since.

However, I was under the impression, that the purpose of the stir plate was to aerate the starter as yeast is being propagated, therefor the need for the vortex. Please inform me if this is incorrect.

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The gas exchange occurs at the liquid/air interface. Stirring continuously exchanges the wort at the surface with that below. Gentle stirring is all that is needed to keep the wort moving. No need at all to run the stir plate at full speed. I've found that 200-300 rpm works well for me with a 2 liter flask and a 2" stir bar.

Most of the time I don't get a lot of foam in the flask so long as the starter does not get too warm and the plate is running continuously. Sometimes, if you stop the stir plate for a time, then start it back up you will trigger a sudden release of accumulated CO2 which can generate a lot of foam suddenly. Once I start stirring, I continue until the starter has finished out completely. Foam control drops can be used to minimize foaming problems, but most times I find that I don't need to use it.