Stuck fermentation or impatient?

[ipajay]

I have an imperial stout going, OG 1.096. Started with London Ale yeast and 4 days into fermentation dropped in a packet of red star. 3 weeks later the gravity was 1.040. I gave it a stir and added some more yeast nutrients and she now sits at 70 degrees. The wort was well aerated. So the question is should it have been lower when I measured the gravity? I thought it would be but it is a big brew so it may take a bit longer? Thoughts?

 

[Nateo]

Did you pitch the proper amount of yeast to begin with?

For a beer that big, for a 5 gallon batch, I'd do a huge starter. Probably 8 liters.

 

[tenchu_11]

Try rocking your fermentor around lightly see if it helps. If not make a starter and arate the crap out of it with an electric egg beater. Might just need oxygen to keep going, obviously you can't do it to your partialy fermented wort or it will oxidize.

 

[permo]

If you are positive that it is finished, and rocking the fermenter and raising temp to 70 doesn't get you going then you likely do have a stuck fermenation. There are multiple ways that I have used to get it going:

Add Sugar : it seems the simple sugars wake the yeast up good and after they consume the sugars they often keep on going and chew some maltose too

Add an actively fermenting starter of a more attenuative yeast - wlp001 maybe

I like option 2 best....but I have added sugar stuck ferms, and it has worked before.


My guess is that you underpitched, under aerrated and the yeast dropped out.

 

[ipajay]

thanks for the tips, i underpitched and its a mistake i wont make again!

 

[Nateo]

ipajay - I read in Brew Like a Monk that when Adam Avery (From Avery Brewing in Boulder) started making his Reverend Quadruple, the first batch turned out really under attenuated because they didn't pitch enough yeast. And Avery was already sort of a big brewery at the time. So don't feel too bad, even experienced brewers make mistakes.

 

[ipajay]

Thanks Nateo. I have since made a starter and added small sugars. I dumped them in after transfering the wort and it was bubbling after 2 hours. I am pretty optimistic but only time will tell.

 

[Nateo]

Avery gives their pitching rate as "TMTC" which is too many to count. A good way to get that much yeast is to brew a low gravity beer, then to use that yeast, either pitch on the cake or wash the yeast and use it. Make a 5-gallon starter, essentially.

All of my 1.07+ beers are 3.3 gallon batches, to make it easier to get the proper pitching rates.