Poor Yeast Performance?

[Meatball]

I've got a question I'm looking for some advice on:

I was brewing an Imperial Stout, and pitched the White Labs Liquid Irish Ale Yeast after letting them warm to room temperature for about 3 hours. I aerated the wort pretty well too. I forgot to take the OG unfortunately so I'm not sure what it is. I added 7lbs of LME, and ~3lbs of specialty grains so it should be a fairly high OG, so I figured the first stage of fermentation would be pretty vigorous, but it wasn't.

The process certaintly started, but it never really got more than 1.5-2" of bubbles on top of the wort. Now after a week the beer is pretty much completely inactive. This just doesn't seem right to me since the OG should have been so high.

Should I repitch yeast? swirl the primary? or is it possible that everything went as it should?

Thanks in advance for the help!

 

[Soulive]

Did you make a starter with the yeast? What were your temps like? If you made an Imperial with no starter, that's your problem...

 

[BNVince]

That Irish ale yeast is a real monster. I pitched it on a 1.082 stout a while back and it completely fermented out in under 48 hours.

If I were you I would plug in my ingredients to get a guesstimation on what the OG should have been. Then take a reading and see if you've hit the proper attentuation.

 

[Meatball]

Did you make a starter with the yeast? What were your temps like? If you made an Imperial with no starter, that's your problem...

I sure didn't. I figured that could've been the problem. So is it possible to make a starter now and then pitch that in the beer?

Also are those "smack packs" from Wyeast considered starters?

 

[Meatball]

That Irish ale yeast is a real monster. I pitched it on a 1.082 stout a while back and it completely fermented out in under 48 hours.

If I were you I would plug in my ingredients to get a guesstimation on what the OG should have been. Then take a reading and see if you've hit the proper attentuation.

I'm not too familiar with the concept of attentuation when is comes to yeast. Could you either give me a breif run-down or point to a website or thread that discusses the concept?

Thanks!

 

[Soulive]

I sure didn't. I figured that could've been the problem. So is it possible to make a starter now and then pitch that in the beer?

Also are those "smack packs" from Wyeast considered starters?

You gotta check your FG, but I'd pitch dry yeast if its not low enough. You could also try rousing the yeast thats in there already and warming the fermenter. The smack packs are not starters...

 

[BNVince]

I'm not too familiar with the concept of attenuation when is comes to yeast. Could you either give me a breif run-down or point to a website or thread that discusses the concept?

Thanks!

Whitelabs says it's Irish Ale yeast has an attenuation of 69-74% which, if I understand it correctly, means the yeast should convert between 69-74% of the sugars in your wort to alcohol. So if you started with an OG of 1.082 you would do (or how I do it):

82 x (1 - .74) = 21.32
82 x (1 - .69) = 25.42

Which means with an OG of 1.082 and a yeast that has between 69-74% attenuation, you should expect to get a FG of anywhere between 1.021 and 1.025 roughly.

 

[cheezydemon]

That Irish ale yeast is a real monster. I pitched it on a 1.082 stout a while back and it completely fermented out in under 48 hours.

If I were you I would plug in my ingredients to get a guesstimation on what the OG should have been. Then take a reading and see if you've hit the proper attentuation.

I second that. You should have no problems, and I wouldn't add more yeast. The worst thing you could do, is to introduce new ingredients now if there is nothing wrong. Do you have a hydrometer? If not, taste it. If it is super sweet then you might have a problem.

Also it has gotten much colder here, if that has happened to you too, that might have slowed the ferment.

 

[Joker]

+1 the hydrometer will tell all.

 

[Meatball]

Alright sounds like it's time to take a hydrometer reading!

Does any one know of an online OG calculator/guesstimator?

Thanks for all the help

 

[shafferpilot]

here's a pretty decent recipe calculator:

http://hbd.org/recipator/