Stir the yeast cake?

[Zhaph]

Is there ever a good reason to stir the yeast at the bottom of the primary fermentor? I'm stuck at 1.02 after about 2.5 weeks in primary (and I'm planning to leave it another couple weeks in there), and a friend of mine advised stirring the yeast cake at the bottom with a sanitized rod to re-suspend the yeast and help get it going it again.

Now, I likely will not stir (like I said, I'm just going to wait more time), but the "advice" really got me wondering if there would ever be a case when stirring was a good idea.

 

[Delorean1981]

What's your FG you're shooting for?

 

[Zhaph]

1.013, and it's a chocolate milk stout (NB's kit).

 

[Golddiggie]

Only being .007 points off is NOT bad... Being at 1.020 just means it will be a little sweeter than if it finished at 1.013...

Of course, if you leave the brew in primary for 3-4 weeks (total) then it very well could finish off closer to 1.013...

What was the OG??

 

[sprocketmaker]

How long has it been at 1.02? What temp are you fermenting at? I've had a couple stuck fermentations lately due to colder temps (65 - 68). If you move it to a warmer spot (70 - 75) and agitate the fermenter [you don't even have to open it], then check the gravity in a week and then every 3 days to see if it changed.

 

[ksbrain]

I wouldn't think there would ever really be a reason to stir up the yeast cake. There should still be lots of yeast in suspension to take care of the job.

 

[Zhaph]

OG was 1.049, temperature has been in the 68-75 range mostly, with a couple dips lower during a recent cold snap.

Again, though, I'm really asking this question more in theory, I'm not actually planning to stir the yeast (unless there is an overwhelming response to do so).

 

[McGarnigle]

As long as you sanitize and are careful not to splash, stirring is OK. I used to do it on occasion and it sometimes helped.

 

[JohnMc]

I've found the ESB yeast in particular needs rousing. I do it by picking up the fermenter and moving gently it around such that the wort/beer starts swirling around, as McGarnigle says, "carefully"
This is limited for me to a 5 gallon batch.

 

[jblizz]

From what I have read the only time you should stir the yeast cake is if you are adding a new batch of wort on an old cake...

 

[Patirck]

I did this a while back when my outside temperature dropped lower than expected and I needed to wake up the yeast. I tilted the glass carboy and swirled it a few times and that (and warming it up to the high 60s) was enough to re-suspend everything and get fermentation going again.

 

[JohnMc]

From what I have read the only time you should stir the yeast cake is if you are adding a new batch of wort on an old cake...

In general, that's true, but some yeast need a little 'help'. The Samuel Smith's yeast in particular; follow the link to read about it. They even re-aerate, which kind of weirds me out, but it apparently works, as they make good beer.
http://www.merchantduvin.com/pages/5_breweries/samsmith_yorkshire.html

 

[pjj2ba]

I will do this on bigger beers, and ones I want to really push the attentuation. Once the really active fermentation has slowed down I will "spin" my carboy. This works really well if the carboy is in a milk crate, or some kind of plastic tub. It is just like spinning a merry-go-round. I put one hand on each side and then spin, and spin, and spin. It does a great job of stirring up the yeast with minimal splashing. Since you leave the airlock on, there is no introduction of oxygen.

 

[JohnMc]

I will do this on bigger beers, and ones I want to really push the attentuation. Once the really active fermentation has slowed down I will "spin" my carboy. This works really well if the carboy is in a milk crate, or some kind of plastic tub. It is just like spinning a merry-go-round. I put one hand on each side and then spin, and spin, and spin. It does a great job of stirring up the yeast with minimal splashing. Since you leave the airlock on, there is no introduction of oxygen.

That sounds way better for my back than what I do. Thanks!

 

[tnbrewer371]

I will do this on bigger beers, and ones I want to really push the attentuation. Once the really active fermentation has slowed down I will "spin" my carboy. This works really well if the carboy is in a milk crate, or some kind of plastic tub. It is just like spinning a merry-go-round. I put one hand on each side and then spin, and spin, and spin. It does a great job of stirring up the yeast with minimal splashing. Since you leave the airlock on, there is no introduction of oxygen.

I do this as well, I have all hardwood floors in my house and I just put the carboy on a small towel and spin carefully so it doesn't splash but after a minute or so the whole batch is spinning inside the carbor and picks the yeast back up into suspension seems ro work good and I've never seen any ill side effects

 

[flabyboy]

Here is a nice video clip of someone rousing up the yeast in an open fermentation. the rousing talk is in the beginning. This is also a great video to watch if you are totally paranoid about infection and oxydation

http://www.brewingtv.com/episodes/2010/5/17/brewing-tv-episode-4-open-fermentation.html