Should I pitch more yeast? (a.k.a. why is pitching more yeast considered bad?)

First, my specifics, second the more philosophical question:

I'm brewing my first (well, second, but first was 10 years ago) beer, a stout that I already had a couple questions about earlier.

My OG was 1.05. 12 hours after I started I started getting some nice bubbles. 36 hours after it started the bubbling stopped. Three days after it started, I took a gravity reading: 1.02. I aerated a little and pushed down the krausen. Three days later, I took a second gravity reading: 1.02 again. The recipe ought to end somewhere around 1.013.

Things that could have contributed to my stalled fermentation: Having the temperature fluctuate from 59°-65°F and not aerating the wort properly. I used a small packet of "Coopers yeast" from the Irish Stout Best Brewers kit I had.

On the eighth day I went to my LHBS and they, like many here on this forum, said that pitching more yeast should only be used as a last resort, if at all. They gave me a yeast energizer (or yeast extender, maybe?), told me to keep it warmer, and a packet of Nottingham just in case.

I added the energizer, aerated lots, wrapped it up in blankets and kept it 63°-66°F. 36 hours later, still no bubbles and no movement at all in the gravity. So should I pitch the Nottingham? (As an aside, I had already been wondering whether to throw in some Nottingham to try and make this stout a little drier, but had been steered away from that notion here in the forums.)

My other question: there seem to be a lot and lots of posts by newbies like myself who say "is my beer stalled? should I throw in more yeast?" The answer is almost always to relax and have a home brew. Is pitching more yeast only for the most dire of circumstances? And why is it considered such a weapon of last resort? What would be likely to go wrong if a newbie pitched more yeast when their brew was only "sleeping" and not stalled (assuming they still wait and ensure the fermentation has really stopped before racking or bottling)?

Thanks!

well i hate to tell you this but you most likely oxidized your brew. never aerate after fermentation gets underway.

pitching more of the same yeast you started with wont hurt things. its just typically pointless to do so because the yeast thats already in there can do the work they just aren't for some reason.

the temps reported still sound a little low. most recipes recommend a temp of 68F. fluctuating temps can cause the yeast to suffer temp shock and shut down till things stabilize. i would suggest getting a temp controller, fermwrap and thermowell stopper to control your fermentation temps and keep them in the target range.

Allow the yeast to work. Wait three weeks. If you must do something warm it up to 70-75 degrees.

SamFen said:

My other question: there seem to be a lot and lots of posts by newbies like myself who say "is my beer stalled? should I throw in more yeast?" The answer is almost always to relax and have a home brew. Is pitching more yeast only for the most dire of circumstances? And why is it considered such a weapon of last resort? What would be likely to go wrong if a newbie pitched more yeast when their brew was only "sleeping" and not stalled (assuming they still wait and ensure the fermentation has really stopped before racking or bottling)?

Thanks!

Click to expand...

There is already plenty of yeast in your beer. Adding more just isn't going to have any effect. While the recipe may say the beer should finish at a particular SG that does not mean or guarantee that is actually will. You didn't post the recipe but I'm going to assume it's an extract beer. Extracts, particularly liquid extract, tend not to ferment as fully as beers made from a direct grain mash. There are other factors involved as well. One is the yeast itself. If you are going to buy a pre-made kit with factory yeast included do yourself a favor and buy a fresh package of yeast instead of using the kit yeast. The yeast in the kit has been around for an unknown length of time, subjected to possible wide ranges of ambient temperatures and was probably not all that great to begin with anyway. A good HBS will have high quality, fresh yeast, stored properly under refridgeration and a package of dry yeast is cheap. Chances are you also did not aerate the wort prior to pitching the yeast initially. Lack of O2 for the yeast's respiration stage will prevent it from reaching its' full potential and cause it to stop short of full attenuation. In short, your beer is done fermenting. RDWAHAHB.

BigEd said:

There is already plenty of yeast in your beer. Adding more just isn't going to have any effect. While the recipe may say the beer should finish at a particular SG that does not mean or guarantee that is actually will. You didn't post the recipe but I'm going to assume it's an extract beer. Extracts, particularly liquid extract, tend not to ferment as fully as beers made from a direct grain mash. There are other factors involved as well. One is the yeast itself. If you are going to buy a pre-made kit with factory yeast included do yourself a favor and buy a fresh package of yeast instead of using the kit yeast. The yeast in the kit has been around for an unknown length of time, subjected to possible wide ranges of ambient temperatures and was probably not all that great to begin with anyway. A good HBS will have high quality, fresh yeast, stored properly under refridgeration and a package of dry yeast is cheap. Chances are you also did not aerate the wort prior to pitching the yeast initially. Lack of O2 for the yeast's respiration stage will prevent it from reaching its' full potential and cause it to stop short of full attenuation. In short, your beer is done fermenting. RDWAHAHB.

Click to expand...

Couldn't have said it any better.

I think I managed to get my Belgian barleywine restarted by making a starter and pitching it.

It stalled out half way through. Because I couldn't get to the LBHS, it just sat there for 3 months. I pitched the starter this morning and I have activity In my airlock already.

I had tried raising the temp with a brew belt and I tried adding yeast nutrient shortly after it stalled without luck.

TipsyDragon said:

well i hate to tell you this but you most likely oxidized your brew. never aerate after fermentation gets underway.

Click to expand...

Huh. So when people re-pitch yeast (my case aside, I have seen several posts with suggestions to re-pitch more yeast), do people not aerate? It seems like the yeast wouldn't get enough oxygen if not.

mummasan said:

Allow the yeast to work. Wait three weeks. If you must do something warm it up to 70-75 degrees.

Click to expand...

I'm absolutely fine waiting, but after 8-9 days at the same gravity, is waiting around another couple weeks likely to affect the gravity much? I always read that people consider fermentation to be over after the gravity sits for 3-4 days.

BigEd said:

There is already plenty of yeast in your beer. Adding more just isn't going to have any effect. [...] There are other factors involved as well. One is the yeast itself. The yeast in the kit has been around for an unknown length of time, subjected to possible wide ranges of ambient temperatures and was probably not all that great to begin with anyway.

Click to expand...

So I'm a little confused by the first and last sentences in the quote above. Is there plenty of good yeast in the brew, or might the yeast not have been of good quality?

If the yeast was of poor quality like you say above, or it died for some other reason like lack of proper aeration (not sure if this would cause yeast to die or not), why is it best to assume that there's plenty of good yeast in there? Wouldn't re-pitching more yeast (perhaps after waiting another week, sure) allow the yeast to reach full attenuation?

There is a difference between live yeast and active yeast. There can be live yeast in your beer but for some reason or another it has gone dormant. You need something to kick it back into being active.

If you just open a smackpak, vial, or dry packet of yeast and pour it in, it won't work. That yeast will see other yeast and see the alcohol that has already been made and think "all the work is done here already, I can go dormant too."

You need to add active yeast. That's the theory behind using a new starter. That yeast is actively looking for sugars to digest when you add it to the stuck fermentation. It will find the sugars and get it going again.

There are a lot of nonfermentables in that recipe you posted in the other thread. There's a good chance it's done. Wait two weeks, see if you can warm it up a bit, then bottle away. You're probably going to enjoy this beer more when it's younger, given the oxidation issues.

The lesson here -- hard as it is in the beginning -- is to pitch your yeast, then forget all about the beer for two (or more weeks). The yeast don't really need our help.