When is it appropriate to repitch yeast? The final gravity of an Irish Red I just brewed is a bit low for my liking, but only by .5% so I don't think it would be worth it to repitch. But say it was lower, is adding more yeast something that can help? I've never really had this problem before so I'm not sure how to address it at this stage.
question about repitching yeast
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djfriesen
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When you say your final gravity is low, do you mean it didn't attenuate as much as you'd expected (eg, your ABV is low)? That's how I'm reading it, so that's how I'll reply. If this isn't the case, let me know.
The yeast have probably eaten all the fermentable sugars available. I don't have much experience in extract brewing, but I have read multiple times about this method being especially susceptible to under-attenuation. If there aren't any sugars left for the yeast to eat, repitching won't help (unless you were to pitch something that COULD eat you longer-chain sugars, but that's a whole other topic). If your gravity reading is steady for 2-3 days, I'm sure you're done. You look to only be a couple points off, so you're not in too bad of shape. Repitching at this point would be a waste of money, as you stated.
Really, the only time I would repitch to help acheive a lower gravity is if I know the initial yeast strain I used was not alcohol-tolerant enough to get the beer down to what I wanted. In that case, I might pitch a second strain with a higher alcohol tolerance to get it there (though I would probably just pitch the second strain from the get-go). But it's really a function of how much is available for the yeast to eat. If there simply aren't any more fermentable sugars in the beer, then there isn't much you can do.
I guess one other time I might re-pitch is after extended aging. If the beer has been exposed to the alcohol for a long time (extended aging, for example), it can die off. If you are looking to bottle carbonate, then you would have to repitch a viable yeast, in order for it to be able to metabolize the priming sugar.
Hope that helps. If anyone else has any thoughts, please share, especially if there is an extract-brewing aspect I'm not aware of.
The yeast have probably eaten all the fermentable sugars available. I don't have much experience in extract brewing, but I have read multiple times about this method being especially susceptible to under-attenuation. If there aren't any sugars left for the yeast to eat, repitching won't help (unless you were to pitch something that COULD eat you longer-chain sugars, but that's a whole other topic). If your gravity reading is steady for 2-3 days, I'm sure you're done. You look to only be a couple points off, so you're not in too bad of shape. Repitching at this point would be a waste of money, as you stated.
Really, the only time I would repitch to help acheive a lower gravity is if I know the initial yeast strain I used was not alcohol-tolerant enough to get the beer down to what I wanted. In that case, I might pitch a second strain with a higher alcohol tolerance to get it there (though I would probably just pitch the second strain from the get-go). But it's really a function of how much is available for the yeast to eat. If there simply aren't any more fermentable sugars in the beer, then there isn't much you can do.
I guess one other time I might re-pitch is after extended aging. If the beer has been exposed to the alcohol for a long time (extended aging, for example), it can die off. If you are looking to bottle carbonate, then you would have to repitch a viable yeast, in order for it to be able to metabolize the priming sugar.
Hope that helps. If anyone else has any thoughts, please share, especially if there is an extract-brewing aspect I'm not aware of.
First question is; what temperature is the beer at? If it is too cold, the yeast will start to drop out of suspension as the fermentation slows, and generates less heat, and may not fully attenuate. You might try moving the fermenter to a warmer location and see if it starts up again.
0.5% is not much. About .004. Not sure many of us can accurately predict where our beers will end up every time.
What yeast? Different yeasts attenuate to different levels. If you are using a low attenuating yeast, you might get some more movement pitching a higher attenuating yeast.
0.5% is not much. About .004. Not sure many of us can accurately predict where our beers will end up every time.
What yeast? Different yeasts attenuate to different levels. If you are using a low attenuating yeast, you might get some more movement pitching a higher attenuating yeast.
