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Old 04-05-2012, 10:51 PM   #1
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Default Stuck fermentation fixed with heat, but how long?

I brewed a 6.5 gal batch of IPA. OG was 1.065. Two weeks later I racked (per recipe) to carboy. SG was 1.030 at 70 degrees, and there it remained for a week instead of steadily going to planned FG of 1.014. I chose to put the carboy on a heat mat to jumpstart the yeast (Safale US-05), and within 12 hrs, bubbles appeared on the surface of the wort and in the airlock. Temp was 80.

My earlier mistake was not getting enough O2 in the wort after cooling down to 70. It took nearly 4 days for fermentation to start, but then it went with a fury for a few days.

Question: Any problem leaving the carboy on the heat mat? Would the yeast keep working if it went back to ambient room temp of 68/70? Advice would be appreciated.

Grain bill for 4.5 gallons, 152º mash for 60 min:
13 lbs American Two-row Pale
2 American Munich (Light)
1 American Victory
.6 American Crystal 20L
.5 American Crystal 60L
.50 CaraPils
90 minute boil (hop schedule omitted from thread)

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Old 04-05-2012, 11:20 PM   #2
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It doesn't sound as though you rehydrated the yeast? At 70 you re at the higher end of the temps and at 80 you are way over. If the gravity was only at 1.030 when you racked it wasn't done yet and you should have just let it sit. Racking of the yeast was not a great idea and the heat, while creating more bubbles may also be creating serious off flavors.

Bubbles are not a solid indicator of fermentation, only gravity readings. IMO you should have given the sealed up primary a little shake to rouse things up instead of transferring. If you did not aerate well that will attribute the slow start. Leave it alone in the secondary for a few weeks and let whatever yeast is present clean things up but get it off the 80 degree heat-60-65 degrees is ideal.

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Old 04-06-2012, 12:39 AM   #3
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I'll unplug the heat mat right away. The recipe called for racking after a week, but of course that assumed oxygenated wort. I racked after 2 wks, at 1.030. I let it sit for a third week, during which time it remained at 1.030.

I did rehydrate the yeast. I let it sit for an hour in about 4 cups of leftover wort from the mash tun. It was about 80 degress.

I'll see what the next week brings. Being a newbie and this being my 2nd large batch, I was proud of the efficiency of the mash, but then I ran into this problem. Experience IS a good teacher. Thanks!

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Old 04-06-2012, 12:45 AM   #4
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Sidenote, but the bubbles in the airlock could mean nothing at all. When you heat the liquid it decreases its ability to solubilize CO2. The airlock activity you see could likely be CO2 coming out of solution

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Old 04-06-2012, 01:32 AM   #5
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Quote:
Originally Posted by jjbrewer View Post
I did rehydrate the yeast. I let it sit for an hour in about 4 cups of leftover wort from the mash tun. It was about 80 degress.

I'll see what the next week brings. Being a newbie and this being my 2nd large batch, I was proud of the efficiency of the mash, but then I ran into this problem. Experience IS a good teacher. Thanks!
Most sources recommended to rehydrate in water, not wort, otherwise you might as well just pitch. Something about the cell walls not being strong enough during rehydration to prevent sugar from getting in, I'm not sure. But with that being said, Fermentis does say to rehydrate in "water or wort"

http://www.fermentis.com/fo/pdf/HB/E...e_US-05_HB.pdf

Iif you're going to rehydrate right into wort I guess I don't see the point.

Anyway, you should also check your thermometer, if it's reading a few degrees low you could have mashed too hot leading to the high FG!
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Old 04-06-2012, 11:44 AM   #6
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Thanks for the tips, esp. the link to the pitching instructions.

I may have to dump this batch, given the long lag in the beginning and now the exposure to 80 degrees. I'll check the SG again in a week and then give it a taste.

Re. the mash temp, I'll check the calibration of the thermometer, but the recipe's target OG was 1.064.

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Old 04-06-2012, 01:18 PM   #7
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Don't pitch it! Even if it doesn't hit the expected FG it will still be beer although lower ABV than desired. In addition to checking your thermometer be sure your hydrometer is properly calibrated. Take a reading with DISTILLED water and see what it reads and make your adjustments as necessary.

Give it a week, check the FG, give it a taste and if the FG hasn't changed, bottle it up, give it a few weeks to carb and enjoy it! Cheers

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Old 04-13-2012, 10:49 AM   #8
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One week later my calibrated hydrometer yields the same reading: 1.030. So it's time to bottle.

Should I assume that 1) the lack of fermentation at 1.030 reflects the presence of unfermentable sugars? and 2) priming sugar in the bottle will enable enough fermentation to carbonate my low ABV beer?

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Old 04-13-2012, 11:55 AM   #9
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One week later my calibrated hydrometer yields the same reading: 1.030. So it's time to bottle.

Should I assume that 1) the lack of fermentation at 1.030 reflects the presence of unfermentable sugars? and 2) priming sugar in the bottle will enable enough fermentation to carbonate my low ABV beer?
You will wind up with a sweeter, more malty beer. There is enough yeast in suspension in the beer for proper carbonation to occur. Bottle them up and give them a couple weeks to carbonate, then sample.
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Old 04-13-2012, 03:39 PM   #10
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Im surprised nobody has mention pitching a different yeast to see if it can ferment out the remaining sugars. If I were you thats what I would do then wait a week and take another reading, if its still 1.030 well then those sugars probably arent fermentable.

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