Is my stir plate going too fast, please respond

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As long as your stir bar isn't flying off and jumping all over you're fine. No need to turn it off and back on. You just want to keep the yeast in suspension.

Now that you've got a nice large flask you should look in to harvesting yeast from your starters. Build a small bank of popular yeasts and you'll never have to buy yeast again (unless it's one you don't have yet).
 
That's not much liquid. Why so small a starter? Most starters I see are in the 1L to 2L range.

Generally, though, my understanding is that so long as you're not throwing the stir bar to the sides of the flask you're not going too fast.

But super-fast, mega-vortex movement isn't necessary. Just keeping a small divot in the surface of the starter liquid is usually enough.

Does the stir plate not have a slower speed, or a speed-control knob?

-Rich
 
My stir bar is staying in place just fine. Now as far as harvesting yeast, I do that. However, I'm doing a large worldwide beer experient with a bunch of youtube folks, and we are all using the california or american ale yeast, which I don't currently have. I will definitely harvest that after this batch.

Now as far as the size, I'm doing a 5 gallon batch, so figured I didn't need a huge starter. So I just did a 1/2L starter. This will go for about 18 - 24 hrs before it gets pitched. I always do a 1L with harvest yeast. Even going forward I may do 1L just to have a little more liquid in here.
 
My stir bar is staying in place just fine. Now as far as harvesting yeast, I do that. However, I'm doing a large worldwide beer experient with a bunch of youtube folks, and we are all using the california or american ale yeast, which I don't currently have. I will definitely harvest that after this batch.

Now as far as the size, I'm doing a 5 gallon batch, so figured I didn't need a huge starter. So I just did a 1/2L starter. This will go for about 18 - 24 hrs before it gets pitched. I always do a 1L with harvest yeast. Even going forward I may do 1L just to have a little more liquid in here.


The type of yeast harvesting I'm talking about is harvesting from your starter, not from the yeast cake left over after fermentation.

See here: https://www.homebrewtalk.com/entries/yeast-harvesting-novel-approach.html


I always do a 2l starter, save half a liter, and pitch 1.5l.
 
That's still moving pretty quick. But once you start making bigger starters the extra liquid in there will help slow it down.
 
Your first one was fine - aside from keeping yeast in suspension, a stirplate can also increase O2 and decrease CO2 levels through a mixture of agitation (helps knock CO2 out of solution) and introducing air bubbles into the wort (increases the area for gas exchange many-fold). As other said, unless your bar is flying off the stirplate, or spraying wort everywhere, its fine.

Bryan
 
Ok thanks all. I'll let it go over night, and then pitch it tomorrow and see how it goes. This is the first time using a stir plate, 2nd time making a starter. And like I said, next time will definitely be doing a 1L starter minimum.
 
I'm starting to wonder, if I should let this go over night, then put in another 1L of wort in tomorrow, and let it go again for 24 hours. My starting OG is going to be around 1070 for this American Ale. Mr Malty is saying 3.25 liter starter with only 1 vial on a stir plate.
 
Longer wont equal more yeast unless there are sugars for them to eat. What you can do is palce the starter in the fridge for 24 hours to let the yeast settle, pour off the spent wort, and replace with fresh 1.040 wort. Spin for another day, and it should have the numbers you need.

This is called 'step starters'; I think mr. malty can calc these, if not, yeastcalc.com does it quite well*.

*As a caveat, yeastcalc and mr. malty use pitching numbers based on using yeast from slurries (which is weaker and less fermentive than yeast grown aerobically in a culture). Generally, they are recommending 0.75 million/ml/degree plato (ales) to 1.5 million/ml/degree plato (for lagers). For stirplate-cultured yeast you can often get away with ~1/2 the number of yeast that these calculators recommend.

Bryan
 
Mr malty is saying I need 294 billion cells. They are saying my smack pack(02/13/2013) been refridgerated the whole time, is 62% viability. So that is why they are saying such a big starter or more vials, whether that is needed or not, I don't know.

Maybe I should brew this on Saturday instead of tomorrow. Tomorrow late morning put this in the fridge. Friday morning, decant it, add 1L or wort, then put it back on the stir plate, and pitch it on Saturday.
 
The yeast will settle out pretty fast in that small starter. You would probably be able to get away with decanting within a few hours of placing it in the fridge. I like to let mine go on the stir plate for at least two days before pitching.
 
The yeast will settle out pretty fast in that small starter. You would probably be able to get away with decanting within a few hours of placing it in the fridge. I like to let mine go on the stir plate for at least two days before pitching.

Ok, here's my plan then. Let this go until morning tomorrow, that will be about 18+ hrs. Place it in the fridge for 3 - 4 hrs. Decant it, add 1L of wort to it, put it back on the stir plate for 18 hrs, then put it back in the fridge. 1 or so hours before pitching it, pull it out and let it warm back up. Then when it's time decant it, swirl it around, and pitch it in.

I'll just move my brew day from tomorrow to Friday, no biggie.
 
Sounds like a good plan to me. I'm brewing on Saturday too, and today I'll get my starter going.
 
You can still brew tomorrow. Just pitch the yeast on Friday. No big deal there.
 
I remember a few weeks ago you started building this stir plate. I suggested to use an LM317 regulator to control the speed instead of a few hard-wired resistors.

Someone else offered the schematic:
"Here’s the schematic with the LM317 adjustable regulator. The capacitor is totally optional."
http://www.stirstarters.com/instructions.html

I'm surprised you haven't built the speed control yet. You're gonna need it depending on the amount of starter you're stirring.
 
I remember a few weeks ago you started building this stir plate. I suggested to use an LM317 regulator to control the speed instead of a few hard-wired resistors.

Someone else offered the schematic:
"Here’s the schematic with the LM317 adjustable regulator. The capacitor is totally optional."
http://www.stirstarters.com/instructions.html

I'm surprised you haven't built the speed control yet. You're gonna need it depending on the amount of starter you're stirring.

I'm using a rheostat, which is adjustable with a knob. I just added a couple to drop it a little more. I doubt I'll ever make a 1/2L starter again, so I'll see how it goes tomorrow with more liquid.
 
That looks too fast to me. I've been told that going too fast can damage the yeast cells. You really only need a small dimple on the surface.
 
This is how it looks so far. 18 hours on stir plate, about 1.5 hrs in the fridge. I'm going to let it go another 1.5 hrs, decant it, add 1L of wort to it, then back on the stir plate for 24 hrs. Then in the fridge, and pull it out an hr before pitching. According to YeastCalc, I should have about 143 billion cells right now. What is the difference between K.Troester and J.Zainsheff as far as the stir plate setting goes?

yeast 004.jpg
 
You do what you want. I do 4 cups water in 1 cup DME in a 2l flkask, if you want a comparison point. If you think the stir plate is going too fast, drop the voltage down and the speed will reduce. I made a stir plate with a 12V computer fan and 2 hard drive magnets. The only wall wart I could find was a variable voltage model that went from 1.5V to 12V. I set it at the lowest speed that will turn the stir bar, 3V. The wort makes a little dimple. If I turn it up all the way, I can fill the flask and draw a full tornado all the way down to the bottom. Certainly exciting at parties but unnecessary IMHO. For me i believe your stir plate is moving too fast,
 
Here it is again. I let the first one go for 18 hrs, put it in the fridge for 3 hours, decanted it, and added another quart of starter to it. Here it is again on the slowest setting with. I just double checked, my plug is a 8V charger, hooked up to a 25 ohm rheostat that adjusts. I'll have to hunt around to see if I can find a 6V one.

http://www.youtube.com/watch?v=8rpR9_ZOh_A&feature=youtu.be
 
That looks fine to me. And again, once you start making bigger starters it will slow down even more.
 
I have only made one yeast starter up till now so it certainly does not make me an expert, which is why I read this thread. I also watched your YouTube video and laughed thinking how the poor yeast were crushed up against the side of the flask like the Rotor ride at the Circus. The stir bar spinning won't hurt them as much as the G Force and friction of rubbing against each other.

My goal is to use the knowledge from the article below to save some money. https://www.homebrewtalk.com/entries/yeast-harvesting-novel-approach.html

I built my own yeast stir plate, but need to refine the speed a bit further as well since my 1 liter starter had a full vortex. Sounds like I just need a smaller charger or a different potentiometer or a bigger starter.

Need more kegs to make bigger beers and let them age longer as well.
 
Why do you keep quoting a rigid schedule of 18 hrs on the stir plate and 3 hrs cold crash? I let the starter go until the krausen drops back into the wort, then set it into the frige until the wort is clearish. Sometimes if the yeast is old it can take 2 days or more to get started. That's one of the reasons why we do starters. Also, yeast will take more or less time to flocculate depending on the strain. I find 24-48 hours more reasonable for flocculation.
 
That number was stuck in my head who knows :D

I did 18+ hrs on the first step, did 3 - 4 hrs in the fridge, let it warm up again, decanted it. Added about 1 quart more of wort, then put that on the stir plate for about 24 - 26 hrs, then took it off on brew day, which was yesterday. Everytime I walked in the house, I just swirled it around by hand. Then when it was finally time, I just pitched the whole thing, and didn't decant it. The beer took off in 3 hrs or less. I checked it after about 3 hrs and it was already bubbling away.

This was my first time using my stir plate, my 2nd starter total. Next time, I will approach it a little different. I will start with a 1.5 or 2L starter and using mrmalty or yeastcalc first. I kind of did the reverse, just did a quick .5L starter, then looked at yeastcal, not sure why I did it that way :) I feel pretty confident this starter is going to be fine though.
 
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