Author Topic: Problem with attenuation  (Read 575 times)

Offline brian-d

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Problem with attenuation
« on: November 26, 2011, 04:04:55 PM »
I recently built a fermentation chamber from a 7cf chest freezer and Ranco style temp controller which seems to work well. The last three beers I've fermented did not hit the expected terminal gravity. The last two were in the 1.080-1.085 OG range and finished in the high 20s. I've never had this problem before. My beer always attenuates well. Both were vigorous fermentions for 2-days before settling down. Two things come to mind that I suppose could make a difference,

1. I mashed higher than normal. One beer 153 and one at 155. I'm usually 150-152. Could this make a big difference?

2. I had to pitch the whole starter because the starter fermentation was not complete (big starters) after about 18-24 hours and I was finished brewing and ready to pitch.

Aside from that I kept the fermentation temp right where it should have been so I do not understand what has happened lately? Any comments? Thanks! Is there a procedure to use to bring the gravity down in this type situation?

Offline a10t2

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Re: Problem with attenuation
« Reply #1 on: November 26, 2011, 04:53:03 PM »
The first thing to check would be the calibration on both your mash thermometer and the temperature controller. If you were mashing high and/or fermenting low, that could be the issue.
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Offline jamminbrew

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Re: Problem with attenuation
« Reply #2 on: November 26, 2011, 04:55:24 PM »
Also, I don't think 18-24 hrs is long enough for a starter.
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Offline oly

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Re: Problem with attenuation
« Reply #3 on: November 27, 2011, 09:44:20 PM »
Was your starter from a fresh vial/smackpack or was it from reused slurry? If reused slurry, how many generations? I've had yeast start to finish high after 5-6 generations and was probably caused by less than optimum oxygenation and/or nutrients.