Stir plate question

[the_fhunt]

This Guy came up with a sweet design and stands behind his product. I just happened to be visiting my folks in Michigan and caught a Yonder Mountain String Band show at Bell’s brewery (who happen to have a homebrew shop at the brewery) and was shooting the breeze with the fellow running the shop. I mentioned that I was looking into building a stir plate, and he turned me on to this little gem.

http://stirstarters.com/

Cheers!!

[barbarianbrewer]

@Denny

Keep in mind that the size of the vortex really doesn’t matter. Recent tests have shown that very little O2 gets drawn into your starter no matter how big the vortex. The main benefit of a stir plate is keeping the yeast in contact with the wort, not adding O2.

Kai at Braukaiser.com did an experiment to study how stir plate speed affected yeast growth (
http://braukaiser.com/blog/blog/2013/03/25/stir-speed-and-yeast-growth/
). He found a strong correlation between stir plate speed and yeast growth. Based on this I tried to get a good vortex going. But not so strong that the bottom of the vortex would disrupt the rotation of the stir bar.

[denny]

@BarbarianBrewer

[quote=“Denny”]Keep in mind that the size of the vortex really doesn’t matter. Recent tests have shown that very little O2 gets drawn into your starter no matter how big the vortex. The main benefit of a stir plate is keeping the yeast in contact with the wort, not adding O2.

Kai at Braukaiser.com did an experiment to study how stir plate speed affected yeast growth (
http://braukaiser.com/blog/blog/2013/03/25/stir-speed-and-yeast-growth/
). He found a strong correlation between stir plate speed and yeast growth. Based on this I tried to get a good vortex going. But not so strong that the bottom of the vortex would disrupt the rotation of the stir bar.[/quote]

But was that growth based on O2 levels or simply keeping the yeast in contact with the wort? IIRC, Kai didn’t measure DO levels. My personal experience is that you don’t appear to get any more yeast growth with a large vortex than a small one.

[turkeygecko]

i think the vortex looks pretty sweet, but agree the purpose of stir plate is to keep yeast in suspension (or as Denny said, “in contact with the wort”). as long as the stir plate keeps things moving inside the flask, i think it should get the job done.

[antwerp]

I’d offer one other option – if you live in a large enough city, there are places that sell used lab equipment. I picked up a very nice stir plate for $25 which is exactly like the ones I used to use when I worked in a research lab. It’s constructed out of very durable parts and has variable control that can produce any kind of stirring effect from gentle to large vortex. It’s possible that if you don’t live in a larger city you might be able to find one online.