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-   -   Imperial Stout Fermentation Stuck (http://www.homebrewtalk.com/f39/imperial-stout-fermentation-stuck-138514/)

BtotheG 09-25-2009 05:05 PM

Imperial Stout Fermentation Stuck
Hi All, I brewed an Imperial Stout a few weeks ago, it's actually the recipe available in Extreme Brewing by Sam Calagione. I don't have the book in front of me at the moment, but if I recall correctly, the OG was just over 1.1 (1.102 maybe) and after two weeks of fairly steady but not crazy fermentation the krausen disappeared and it stopped bubbling. Reading around on these forums, I realized that this didn't necessarily mean much, so I decided to check the gravity. It was at 1.05 and unchanged after I checked it three days later. The final gravity listed in the book was somewhere around 1.02 (1.026 maybe). So I guess I'm new enough to this that I have a few questions. I would be grateful for any help you all could provide.

* Is it safe to say the fermentation has stopped?

* The book didn't specifiy how many Wyeast packs to use so I only pitched one - directly into the cooled wort. Reading around on the forums I get the impression I should have used more yeast for such a big brew and probably made a starter. Is it too late to add more yeast?

* If my only option is to move it to the secondary as is, will any fermentation continue in the secondary and in the bottles? Or is the current gravity and ABV the best I can hope for?

Suthrncomfrt1884 09-25-2009 05:11 PM

Try rocking your bucket back and forth a few times. It will help get some yeast back in suspension and continure fermentation. You may have to do this a few times before you're able to get it to 1.020. Next time, with beers this big, I suggest AT LEAST 3-4L starters. The one pack of yeast just doesn't cut it.

Edcculus 09-25-2009 05:32 PM

With an OG of 1.100 and a FG of 1.026, thats about 74% attenuation. Not bad at all. You don't really want a RIS to go that low. Unlike a Tripel, its not supposed to be a very dry beer. If you go too low, there won't be any sweetness to back up all the alcohol and bitterness.

BtotheG 09-25-2009 09:25 PM

Many thanks guys. This is the first time I've tried anything crazy so maybe I'm over thinking things. When I rock the carboy, is there anything I should be aware of? Such as how much it should be rocked or how often? Should I try to keep it from splashing very much?

Also, I haven't made that many batches of beer but it seems like fermentation always slows to a stop around two weeks. Is it unreasonable to think a big beer like this would finish in two weeks? The book doesn't give a time frame on when fermentation should end. Could it potentially take months?

ChshreCat 09-25-2009 09:38 PM

You don't need to rock it much at all, if you want to try that. I don't even really get mine up on edge from the floor when I do it. Just take the neck and gently move in a circle so the liquid starts moving and you see a light haze of yeast particles start to rise up from the cake. You don't need to get the whole cake upset, just stir the surface up a little bit. 5-10 gentle circles on the neck will usually do it.

jescholler 09-25-2009 11:04 PM

Here's a good thing to try if rocking doesn't get it finished:

In the future, you'll want to be sure to use the pitching rate calculator on mrmalty.com to find out how much yeast you need.

schweaty 09-26-2009 01:20 AM

Which type of Wyeast yeast did you use and at what temperature did you ferment? If you did this as an all grain recipe what was your mash temperature?

If you didn't do a starter you probably should have, especially with such a high gravity beer. Starters are an absolute must when using liquid yeast in my opinion. I tried to test the White Labs claim of being "pitchable" with a pale ale around 1.055 original gravity and even pitched two vials of yeast. The fermentation got going withing 24 hours but it was by far the slowest I've ever had. Normally with a starter I see signs of active fermentation within 8 - 12 hours.

Tlylebrew 09-26-2009 02:56 AM

I recommend liquid yeast with a starter, I personally think 3 - 4 liter starters are a bit over kill. I've made three large 1.110 beers with no issues on 2 liter starters. Your mileage may very.

I've only been doing this since January, so what I say can be taken with a grain of salt.

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