Restart RIS stuck fermentation or just live with it?

[jclimacus]

Hello Folks,

A bit of a dilemma here. I recently brewed up a 2.75 gallon batch of Russian Imperial Stout, the OG was 1.106 (60 IBUs). I did aerate with O2 for 60 seconds but the tank was quite low, not the usual strong stream. I pitched 2 packs of US-05, fermented around 66. After all visible signs of fermentation ended the gravity was only at 1.040. Not enough O2 at the beginning I take it. I tried stirring the yeast cake up a bit, warming the temp to upper 60s, but that did nothing. Last week I mixed up a starter (2oz dme and 16oz water) with 6 grams of US-05 and this time added some yeast nutrient. After about 6 hours the starter seemed foamy enough so I pitched it in. Activity in the RIS resumed for a few days but after several hydrometer readings the gravity has only dropped to 1.035 (currently 9.3% ABV). Samples taste fine I suppose, but I would think that something in the range of 1.030-1.025 would taste better. I have read that Wyeast 3711 can also be used to restart stuck fermentations but I am afraid that this yeast would bring the final gravity down too low, somewhere into the teens.

Does anybody have any advice? Would 3711 in this situation bring it down too far? Or do I just live with it?


Thanks.

 

[day_trippr]

Grain bill and mash temperature?

As you indicated you haven't hit the abv limit for us-05. It's spec'd from 9 to 11% abv tolerance (I got it up to 15% once) and 78-82% apparent attenuation. 3711 runs up to 12% and 77-83%, and as it's a diastaticus-positive strain it might have more legs than US-05.

But there should be some room to drop the FG with the us-05 still in play. Maybe whack it with some amylase enzyme...

Cheers!

 

[jclimacus]

Let's see, it was something like this:
Maris Otter 80%
Roasted barley 6%
Chocolate 4%
Pale chocolate 2%
Medium crystal 4%
Crystal 120 4%

I mashed around 152-153. Perhaps a bit high for the style, but I usually get attenuation into the high 70s at least with US-05.

What will amylase enzyme do?

Thanks.

 

[cicquetto]

Wyeast 3711 is not suitable for a RIS. I'm brewing one with OYL-501 with good results, you could do the same.

 

[brownni5]

Wyeast 3711 is not suitable for a RIS. I'm brewing one with OYL-501 with good results, you could do the same.

Why not? Jester King brews one that way.