Questions about first imperial stout

[Riko]

I've been homebrewing for about 9 months. I don't have a secondary, just the primary. For my latest batch, my 7th overall, I made an imperial stout. It's my first stout and, probably more importantly, my first imperial.

The recipe called for 11 pounds of light DME plus 2.5 pounds of steeping grains, and White Labs California Ale yeast.

I left the kettle unattended for a moment about 45 minutes into the boil, and had a boilover. I probably lost about a quart of wort, so I decided to add another pound of DME. (It was an awful mess to clean up and you can bet I won't leave the kettle unattended again.)

The OG was 1.092.

I used a starter on the yeast (also a first for me) and fermentation began less than 8 hours after I pitched it. I got krausen in the airlock, so I put on a blowoff tube.

OK, now my questions:

-- It's been fermenting for 8 days and is still bubbling once every 1.5 seconds. My previous batches had all seen big reductions in bubbling action by this point. Is this because of the higher DME amount, or might there be a problem? Any guess on how long fermentation might take overall?

-- When it comes time to bottle, how much bottling sugar should I use? I've always used 1 cup in my other batches, but those were all pale ales or IPAs with less DME. Would an imperial be any different?

 

[Dos_Locos_Brewery]

Hmm, I can remember being bedeviled by a Russian imperial stout once, too. Made for a very late night, but it turned out great. I'm sure yours will, too. The longer ferment for a beer this strong is normal - give it however long it needs! It would be tough to hazard a guess how long, since that depends on so many factors, but there is no harm in going an extra week or three.

For priming, the amount of sugar wouldn't normally depend on the strength of the beer - 1 cup of sugar is going to produce the same amout of CO2, no matter what beer it's in. There are some second-order considerations, but you can ignore them.

Second order considerations: 1) A bigger beer often ferments a bit less completely by the time you bottle. With some residual slow-fermenting complex sugars, the RIS might become slowly more carbonated over time. 2) A big beer like a RIS has a lot of body. To my palate, a heavy-bodied beer needs higher carbonation. It seems better balanced to me that way, but that may just be a personal preference.

 

[Riko]

Thanks, Dos Locos. I appreciate your help.

Anyone else?

 

[snailsongs]

I wouldn't even worry about bottling for a month........time time time time is what that RIS needs.

 

[ChshreCat]

One cup as a lot of sugar for any style of beer! Check out this priming calculator to get an idea of how much sugar to use as a baseline for various styles.
TastyBrew.com | Homebrewing Calculators | Botting Priming Calculator
Heavier, darker beers tend to be more lightly carbonated than other beers.
I'd suggest investing in a scale as well and measure your sugar by weight rather than volume for consistency.

 

[Riko]

Thanks, snailsongs and ChshreCat. I'm fine with giving it time, just wondered if it's unusual for the fermentation to still be going so vigorously after a week. And thanks for the link on the bottling priming calculator. I do have a scale and can start weighing the sugar, too.

 

[Saccharomyces]

Big beers take longer to ferment. Ideally you should pitch enough yeast to get them to attenuate in under 7 days, but that requires making a starter on the order of a gallon in size (unless you have a stir plate) as well as pure O2 in the fermenter. A smaller starter and/or less aeration I would expect fermentation to take about 10 days for a beer that big.

 

[Riko]

A smaller starter and/or less aeration I would expect fermentation to take about 10 days for a beer that big.

I'm on day 11 and still getting bubbles in the blowoff bucket every 4 seconds. Still no need for concern?

 

[Saccharomyces]

Down to once every four seconds sounds like it's getting close to finishing. Cali ale isn't a very fast fermenter in a big beer compared to the English strains I usually use. You could take a gravity reading, it should be 1.025 or below now...

 

[Riko]

Thanks, Saccharomyces. I guess I'm accustomed to seeing non-big brews bubble once per second for a day or two, then taper off to once every 30-60 seconds a few days after that, so once every four seconds still seems like rapid bubbling to me.