Author Topic: stuck fermentation  (Read 959 times)

Offline jobard

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stuck fermentation
« on: January 28, 2016, 11:21:45 AM »
hi y'all,

I've brewed a Russian Imperial Stout in Jan. 06th, with an o.g. of 1.084 and a target f.g. of 1.020, but it's been 1 and a half week that it got stuck at 1.033.
I've used 2x. S-33 yeast for a 18L batch (4,75 gal.) and it fermented between 64°F and 68°F for the first 14 days, and between 68°F and 72°F to this date.
How can I convince my yeast to keep on attenuating?
thanks

Offline HoosierBrew

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Re: stuck fermentation
« Reply #1 on: January 28, 2016, 01:01:33 PM »
hi y'all,

I've brewed a Russian Imperial Stout in Jan. 06th, with an o.g. of 1.084 and a target f.g. of 1.020, but it's been 1 and a half week that it got stuck at 1.033.
I've used 2x. S-33 yeast for a 18L batch (4,75 gal.) and it fermented between 64°F and 68°F for the first 14 days, and between 68°F and 72°F to this date.
How can I convince my yeast to keep on attenuating?
thanks


Move the fermenter to the warmest room in the house and give it a couple weeks, then check gravity. The moving of the beer will gently rouse some of the yeast into suspension and the warmer temp might spur the yeast to eat a little more sugar. Big beers often take longer to reach FG. You should post your recipe and process so we can see any potential issues. And welcome !
Jon H.

Offline JJeffers09

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Re: stuck fermentation
« Reply #2 on: January 28, 2016, 02:39:18 PM »
What was the pitch rate?  It suggests 50-80 g/hl.
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Offline denny

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Re: stuck fermentation
« Reply #3 on: January 28, 2016, 04:51:20 PM »
Extract or all grain?
Life begins at 60.....1.060, that is!

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Offline jobard

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Re: stuck fermentation
« Reply #4 on: January 29, 2016, 11:18:23 AM »
hi y'all,

I've brewed a Russian Imperial Stout in Jan. 06th, with an o.g. of 1.084 and a target f.g. of 1.020, but it's been 1 and a half week that it got stuck at 1.033.
I've used 2x. S-33 yeast for a 18L batch (4,75 gal.) and it fermented between 64°F and 68°F for the first 14 days, and between 68°F and 72°F to this date.
How can I convince my yeast to keep on attenuating?
thanks


Move the fermenter to the warmest room in the house and give it a couple weeks, then check gravity. The moving of the beer will gently rouse some of the yeast into suspension and the warmer temp might spur the yeast to eat a little more sugar. Big beers often take longer to reach FG. You should post your recipe and process so we can see any potential issues. And welcome !

I'll try that, thanks.

The 5gal. all grain recipe was:

16lb. Pale Malt
1lb. crystal 60L
8oz black malt (500SRM)
8oz chocolate malt (350 SRM)
1oz northern brewer hop 90min
1.5oz williamette 45min
1oz fuggle 20min
2.6oz 100% cocoa 60min
2.6oz 50% cocoa 50% choc. 60min.
1oz. juniper seeds 60min

Offline jobard

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Re: stuck fermentation
« Reply #5 on: January 29, 2016, 11:27:39 AM »
What was the pitch rate?  It suggests 50-80 g/hl.

It was a 5gal. batch. I used 2x 11,5g, which is equal to 1.6 to 2.5 times the pitching rate you posted.

Offline jobard

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Re: stuck fermentation
« Reply #6 on: January 29, 2016, 11:28:14 AM »

Offline HoosierBrew

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Re: stuck fermentation
« Reply #7 on: January 29, 2016, 12:52:58 PM »
What was the pitch rate?  It suggests 50-80 g/hl.

It was a 5gal. batch. I used 2x 11,5g, which is equal to 1.6 to 2.5 times the pitching rate you posted.



That's plenty of yeast for a 1.084 beer. Have you calibrated your hydrometer in water to be sure it reads accurately ?  And what thermometer do you use for mash temps? A cheap thermometer could've had you mashing several degrees warmer than you assumed. What mash temp?


Edit - And did you aerate thoroughly before pitching? Bigger beers need to be aerated even more thoroughly than average strength beers.
« Last Edit: January 29, 2016, 12:58:52 PM by HoosierBrew »
Jon H.

Offline dmtaylor

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Re: stuck fermentation
« Reply #8 on: January 29, 2016, 12:55:38 PM »
Did you rack it?  I hope not.  You might need to put more yeast back in if you did.
Dave

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Offline jobard

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Re: stuck fermentation
« Reply #9 on: January 29, 2016, 01:56:36 PM »
What was the pitch rate?  It suggests 50-80 g/hl.

It was a 5gal. batch. I used 2x 11,5g, which is equal to 1.6 to 2.5 times the pitching rate you posted.



That's plenty of yeast for a 1.084 beer. Have you calibrated your hydrometer in water to be sure it reads accurately ?  And what thermometer do you use for mash temps? A cheap thermometer could've had you mashing several degrees warmer than you assumed. What mash temp?


Edit - And did you aerate thoroughly before pitching? Bigger beers need to be aerated even more thoroughly than average strength beers.

I`m not a very experienced brewer. This is only my 9th batch and I was concerned about the yeast`s ability in fermenting such high gravity wort, but obviously, I was wrong.
Actually, I used a regular hydrometer (not the fancy refractometer type) and it requires no calibration, I guess...
I used a digital, 0.1°C/F accurate thermometer. Mash temp. was between 142 and 152
Regarding aeration, I used a small duly sanitized aquarium air pump hose and stone with a 0.2micra air filter. I placed the stone in the fermentor before slowly transferring the wort to it, so that it was being aerated all the time (about 30 min.).
So, did I do something wrong here?

Offline jobard

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Re: stuck fermentation
« Reply #10 on: January 29, 2016, 01:58:36 PM »
Did you rack it?  I hope not.  You might need to put more yeast back in if you did.

Nope... I didn't.

Offline HoosierBrew

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Re: stuck fermentation
« Reply #11 on: January 29, 2016, 02:09:37 PM »
I`m not a very experienced brewer. This is only my 9th batch and I was concerned about the yeast`s ability in fermenting such high gravity wort, but obviously, I was wrong.
Actually, I used a regular hydrometer (not the fancy refractometer type) and it requires no calibration, I guess...
I used a digital, 0.1°C/F accurate thermometer. Mash temp. was between 142 and 152
Regarding aeration, I used a small duly sanitized aquarium air pump hose and stone with a 0.2micra air filter. I placed the stone in the fermentor before slowly transferring the wort to it, so that it was being aerated all the time (about 30 min.).
So, did I do something wrong here?


Hey ,we all started somewhere. Hydrometers can be checked for calibration - before brewing each time place it in a glass of water and see if it reads 1.000, correcting for temperature . If not , you'll need to add or subtract the deviation from your readings. But the mash temp seems to be an issue - describe what you mean by the 142 -152 mash temp. That's a huge temp range. Do you mash in a cooler or a pot? Did you stir the mash thoroughly enough to get a consistent reading ? How long did you mash?
Jon H.

Offline jobard

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Re: stuck fermentation
« Reply #12 on: January 29, 2016, 03:29:27 PM »
I`m not a very experienced brewer. This is only my 9th batch and I was concerned about the yeast`s ability in fermenting such high gravity wort, but obviously, I was wrong.
Actually, I used a regular hydrometer (not the fancy refractometer type) and it requires no calibration, I guess...
I used a digital, 0.1°C/F accurate thermometer. Mash temp. was between 142 and 152
Regarding aeration, I used a small duly sanitized aquarium air pump hose and stone with a 0.2micra air filter. I placed the stone in the fermentor before slowly transferring the wort to it, so that it was being aerated all the time (about 30 min.).
So, did I do something wrong here?


Hey ,we all started somewhere. Hydrometers can be checked for calibration - before brewing each time place it in a glass of water and see if it reads 1.000, correcting for temperature . If not , you'll need to add or subtract the deviation from your readings. But the mash temp seems to be an issue - describe what you mean by the 142 -152 mash temp. That's a huge temp range. Do you mash in a cooler or a pot? Did you stir the mash thoroughly enough to get a consistent reading ? How long did you mash?

Thanks for the calibration tip; I'll do it from now on. Sorry about the temp. range. What I meant was 148°F to 152°F. I mashed it in a large aluminium pot with a false bottom, stirring almost all the time for 70 min., and I kept doing vorlauf for the last 20 min.. Iodine test confirmed full saccharification.

Offline jobard

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Re: stuck fermentation
« Reply #13 on: February 04, 2016, 10:51:10 AM »
I measured the gravity last night and it is now at 1.021.
I'd like to thank you all for the support.
Cheers!

Offline HoosierBrew

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Re: stuck fermentation
« Reply #14 on: February 04, 2016, 12:45:25 PM »
I measured the gravity last night and it is now at 1.021.
I'd like to thank you all for the support.
Cheers!


Good to hear. That's a great FG for a RIS. Enjoy !
Jon H.