Low efficiency, stuck/slow fermentation?

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tdymz

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Hey guys I've been attempting AG for a while now but always seem to have problems. My latest batch, a pumpkin ale based off Golden Boy Pumpkin Ale recipe I found here, seems to be fermenting slow. I brewed this recipe a couple weeks back and it came out great! My worry is that a couple days after putting the first batch in the primary it was mostly done (OG: 1.05 FG:1.014). This time I checked the beer 4 days after putting in primary and the reading has barely dropped (OG: 1.045 Current: 1.034). I've always had problems with low efficiency ( usually in the 60-70% range), but this time my efficiency was around 55%. Can this be causing a stuck or slowed fermentation? Should I swirl the yeast cake? Wait it out a little longer? Any help would be appreciated. Here is the grain bill:
7.00 lb Pale Malt (2 Row) US (2.0 SRM) Grain 52.83 %
3.00 lb Munich Malt (9.0 SRM) Grain 22.64 %
1.00 lb Wheat Malt, Ger (2.0 SRM) Grain 7.55 %
0.50 lb Biscuit Malt (23.0 SRM) Grain 3.77 %
0.50 lb Caramel/Crystal Malt - 40L (40.0 SRM) Grain 3.77 %
0.50 lb Caramunich Malt (56.0 SRM) Grain 3.77 %

Mashed at 150-155 for about 75 minutes, 60 minute boil
 
Efficiency alone should not affect your fermentation attenuation profile. There are other mash particulars that can. 150-155 is a little on the high side and could result in a less fermentable wort. But that should only affect your finish gravity, but no so much how fast it gets there. I don't see anything about your grain bill that seems like it would affect fermentability too much. Tell us more about the yeast strain and fermentation temps. Generally it's not a concern if after 4 days you've only gotten that much attenuation. All fermentations are a little different.

Your efficiency may not be so much the problems as is consistency. 70% is not too bad, but having it jump down 15% is frustrating (I know from experience), and 55% is relatively poor efficiency. Once you understand the mash, it's not too difficult to diagnose what is causing your efficiency problems. Very often it is due to a poor crush. When I got my own grain mill my efficiency went up 10%. I'm normally hitting 75% to 80%.
 
I used US-05 (not rehydrated) and let it ferment around 60-61F. After noticing the slow fermentation I changed the location 2 days ago and now it's around 64-65F. Thanks for the help!
 
Looks like you already know this, but 60-61 is on the low side for that strain and so it's not unexpected for the fermentation to be slow. Raising the temp, especially this early should help. The good news is that you should have a nice clean tasting beer since you fermented so low. Pitching without re-hydrating may also have caused a longer lag time. When you don't re-hydrate, as many as half of your yeast cells will die in the pitch. Most people report that it doesn't seem to have a negative effect on the beer taste, but I would think it has to affect the amount of time it takes the yeast to build up their numbers.
 
Sounds good, I will take a reading later and let u know if the temp change worked.
 
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