Stir plate with no whirlpool

[Wild Duk]

I just made a 2 liter starter for a lager to brew. I normally just make 1 liter starters.

Will I still get the same effect if it is not making a whirlpool. Not introducing O2 into the solution.

Thx




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[kh54s10]

As long as you are getting constant stirring it should be great. I look for only a small, maybe half inch, dimple on the surface. On smaller starters if the vortex gets down to the stirbar, it will often get "thrown".

Enough oxygen will be introduced if you use an open cell foam stopper or just cover loosely with a piece of sanitized foil. NO airlocks!

 

[Hermit]

The stir bar is pulling the water down in the center and pushing it out and up the sides of the flask. Think little tornado. It doesn't have to be doing this aggressively to turn the liquid over and helping it exchange oxygen and carbon dioxide. Think of it as your yeast going to the surface to get a gulp of air if that analogy helps. In reality what happens is the exposed surface will equalize the oxygen/carbon dioxide with the air above it. It will absorb or out gas depending on the relative concentrations.