Proper way to use a stir plate

[Don]

I just finished my stir plate project and getting ready to use it on my next starter. What is the proper technique for using a stir plate, how fast (how big a whirlpool) and long do you want to use it to get the most O2 in the yeast?
Thanks

 

[k1v1116]

I maybe wrong but I think because with a starter you aren't interested in fermentation but in building a healthy colony of yeast you should leave the stirplate going full speed the whole time.

 

[DutchK9]

I set mine where it just starts making a vortex because it will throw the stir bar at high speeds. I may be wrong, but I thought it just had to be turning in order to grab oxygen and didn't have to be at warp speed.

 

[Blender]

I let mine run on the stir plate the whole time which is about 24 hours. I set it for a moderate vortex because it will throw the stir bar at higher speeds.

 

[Schlenkerla]

I run mine at full speed, it doesn't throw the bar if I ramp it up gradually. I have a 1" stir bar.

I make a starter at least 24hrs before brewing.

You can start it several days before hand just leave it running until you are read to pitch. The longest I had a stir plate going was 6 days.

 

[Joe Camel]

Use it at a speed to get a bit of a vortex, but you don't need to generate foam. Don't use an airlock, a loose cap of tinfoil will keep the bad guys out but let oxygen in. Make sure you chill crash the yeast the night before pitching as this wort will add all sorts of funkiness to your beer.

 

[ajf]

Providing it's stirring fast enough to prevent the yeast from settling and creating a small vortex, it's fast enough.
I find that using a sanitized mason or jam jar inverted over the next of the flask is much better than using foil, especially when SHMBO uses all the foil just before I need it.
I also pitch the entire starter (usually about 1 liter) rather than crash chilling and decanting. See Fourteen Essential Questions About Yeast Starters At what point do I pitch the starter into the wort? if you don't think this is a good idea.

-a.

 

[Throckmorton]

I'm going to build a stir plate as well? What about the stir bar... do you just pitch that into your fermentor along with the yeast, or should it be fished or strained out (keeping sanitation in mind)?

 

[faber]

I'm going to build a stir plate as well? What about the stir bar... do you just pitch that into your fermentor along with the yeast, or should it be fished or strained out (keeping sanitation in mind)?

Well, if it's sanitary enough for your starter, it will be sanitary enough or your primary.

But it's not too hard to pour the starter out slowly enough to keep your stir bar in your flask.

 

[Throckmorton]

True... I realized that the bar would be sanitary. I was talking about being sanitary when removing the stir bar. Another option could be to use an extra magnet to hold the stir bar in place when pitching the yeast.

 

[beerthirty]

Just have a spare magnet on hand. Place the magnet on the outside near the stir bar. Pour and the stirbar stays in the flask.

 

[Schlenkerla]

Just have a spare magnet on hand. Place the magnet on the outside near the stir bar. Pour and the stirbar stays in the flask.

I do the same. It too easy, I'd forget about the bar if I didn't remove it at pitching. It could be weeks later not mention I only have one and can't wait for the darned thing. I'm rarely w/o beer lined up to go.

SWMBO Bitches about the noise, when I have one going, its somewhat amusing, I see it the same as a bubbling fishing tank. Its my preferred white noise if there is one!!!

 

[Homercidal]

... a loose cap of tinfoil will keep the bad guys out but let oxygen in.

How does it do that? If the oxygen is getting in, then bacteria can also get in. Granted, it will keep stuff from falling in there, but the positive pressure from the yeast should make sure that even oxygen is not getting past the neck.

 

[Joe Camel]

How does it do that? If the oxygen is getting in, then bacteria can also get in. Granted, it will keep stuff from falling in there, but the positive pressure from the yeast should make sure that even oxygen is not getting past the neck.

Positive pressure is not an issue as the container is effectively open, just loosely capped. Pressure won't build up. Plus, all gases diffuse down their gradients independent of each other. This is how your lungs can exchange O2 and CO2 at the same time in opposite directions.

The bacteria and dust will stay out because they have to fall down to the bottom of the foil cap, then up underneath to the mouth of the flask. Stuff can't fall up unless there are air currents, which there aren't under the foil cap.

Hope that explains it, but if it doesn't, let me know

 

[bajones1223]

You could always place a foam stopper in the opening. It will allow O2 to enter the container and will hopefully filter out any bacteria carrying dust.

Brad

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