Rousing yeast using a stir bar in the carboy

[Lion]

I have a stalled or very minimum action fermentation on a golden strong. By reading on how to rouse the yeast to get a few extra points of attenuation I thought of actually dropping a stirbar and using the whole carboy as a yeast starter (or in this case re-starter).


Is this another stupid drunk idea?

[Brandon]

You got a stir plate strong enough to turn 5-6 gallons of liquid? That would be a helluva plate. A sanitized racking cane would probably be the best option though

[Afterlab]

Yeah you would need a really large stir plate to shake that heavy 5 gallon carboy. What is your O.G., intended F.G. and your current gravity? How long has it appeared to have been stalled? What is your yeast strain? Depending on how far from your intended gravity you are, you could just re-pitch a clean fermenting yeast or a wine yeast. By stalled are you going by the airlock bubbling or do you mean the gravity reading is stalling out?

Here are a few common reasons your fermentation may have unexpectedly slowed down:

1. Yeast strain you are using has a lower attentuation than what is required.
2. Not pitching enough yeast. Did you use a yeast starter?
3. Fermenting at the wrong temp.
4. Inadequate yeast nutrition. Is your Calcium PPM less than 50?
5. You mashed too high and the sugars leftover in the beer are too complex for the yeast strain to break down.
6. Did you have adequate aeration?
7. The yeast strain you are using starts with a strong fermentation and then slows down.

There are a lot more things that could go wrong so we need a lot more info on your fermentation process to really delve into what some of the possible problems could be.

[animaldoc]

Yeah you would need a really large stir plate to shake that heavy 5 gallon carboy. .

Yeah ??? Would you really?

I don't think so. You only need a stirplate strong enough to spin the bar. We're talking rousing the yeast. We're not trying to vortex and aerate a 5 gallon starter.

[Afterlab]

Yeah you would need a really large stir plate to shake that heavy 5 gallon carboy. .

Yeah ??? Would you really?

I don't think so. You only need a stirplate strong enough to spin the bar. We're talking rousing the yeast. We're not trying to vortex and aerate a 5 gallon starter.

But wouldn't the mass of the beer and the carboy be a little too much for a stir plate that is used to a 2000ml Flask and maybe 1-2 liters of liquid? I would think that at this point there is a bigger issue going on in your fermentation than just having a lack of yeast in suspension.

[snowcapt]

Not to mention breaking up the yeast cake on the bottom. Im not sure how thick or gelatinous it is, but I have had some that were pretty tough. I think your stir bar would get stuck in the muck and do jack shit. Just sayin....
Good luck on whatever you do!

[Lion]

Thanks for the reply, i think i am looking at this problem from a different angle. I need to do a checklist of the stuff that might have gone wrong.

and yes, i thought about the stirplate to break the sediment yeast in the bottom instead of shaking the carboy and making it spin.

1. Yeast strain you are using has a lower attentuation than what is required. wyeast 1214 and 3787 and both have an average of 78%
2. Not pitching enough yeast. Did you use a yeast starter? no, I am building my 1st plate at the moment, i did however used 2 packs.
3. Fermenting at the wrong temp. 68F for 7 days and got very active, then 80F for the past weeks
4. Inadequate yeast nutrition. Is your Calcium PPM less than 50? I use wyeast yeast nutrition on my boil.
5. You mashed too high and the sugars leftover in the beer are too complex for the yeast strain to break down. maybe, I started on 142F for 30min, then 152 for another 30, 160F for another 30min and mashed out at 172F.
6. Did you have adequate aeration? y shake the heck out of this thing, i also use an aereator and a strainer to add more air going in the carboy
7. The yeast strain you are using starts with a strong fermentation and then slows down. according to wyeast website they start slow, nothing says about being strong and then slowing

[thargrav]

You can find a 5 gallon stir plate here.

http://towercooler.com/index.php?option ... &Itemid=97