Russian Imperial Stout question

[Nberry]

Hello fellow brewers! I have brewed a Russian Imperial Stout, and I have a question about the gravity of the style. My paperwork states that the I.G. is 1.093 and that is what it was after the brew. It is now serval days later and the fermentation is doing its thing and the reading I now have is 1.058. Is this the way it is supposed to be and if not is there something I need to do?

 

[Minbari]

Hello fellow brewers! I have brewed a Russian Imperial Stout, and I have a question about the gravity of the style. My paperwork states that the I.G. is 1.093 and that is what it was after the brew. It is now serval days later and the fermentation is doing its thing and the reading I now have is 1.058. Is this the way it is supposed to be and if not is there something I need to do?

What yeast did you use and how much of it?

I did an English imperial that was 1.200 and it finished 1.022. So that seems way too high

 

[Nberry]

What yeast did you use and how much of it?

I did an English imperial that was 1.200 and it finished 1.022. So that seems way too high

I used one packet of Safale-04. It didn't say to use more but on high gravity beers should i be using two instead of one?

 

[Minbari]

I used one packet of Safale-04. It didn't say to use more but on high gravity beers should i be using two instead of one?

I would have used at least 2, maybe 3. You can try adding more

On my imperial i used 2 liquid packets and did a 2 stage starter. 800B cells

 

[HighVoltageMan!]

I used one packet of Safale-04. It didn't say to use more but on high gravity beers should i be using two instead of one?

The key is pitch rate. One pack could be just fine for a small batch, as the volume and gravity is increased the yeast volume increases. As temperature is reduced, the yeast volume is increased.

The general rule used by brewers to measure pitch rate million cells per milliliter per degree plato. Sounds complicated, be it pretty easy to figure out.
5 gallons = @ 19 liters
1.048 OG = @ 12 plato (divide gravity by 4 to get the approximate plato)

Ales are pitch at .75 million per ml/plato
High gravity ales at 1.0
Lagers at 1.5
High gravity lagers 2.0

So the calculations for an ale are: 19,000ml x 12 plato (1.048) x .75 million cells = 171 billion cells. Each pack of dry yeast contains between 110 to 180 billion cells depending on the source (I use 150 billion as a cell count), so it looks like one pack will do the job.

Your beer calculations would be 1.093 OG = 23.25 plato (actual is 22.2, but close enough), assuming it's 5 gallons and it's high gravity, the calculations are:

19,000ml x 23.5 x 1.0 = 441.75 billion cells or 3 to 4 packs of dry yeast.

Or you could use the Brewer's Friend yeast calculator:

https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

 

[Megary]

Hello fellow brewers! I have brewed a Russian Imperial Stout, and I have a question about the gravity of the style. My paperwork states that the I.G. is 1.093 and that is what it was after the brew. It is now serval days later and the fermentation is doing its thing and the reading I now have is 1.058. Is this the way it is supposed to be and if not is there something I need to do?

If fermentation is still doing its thing, then wait a few more days and take another reading. I don't disagree however that technically you underpitched.
For an Imperial Stout, likely high in adjuncts, I wouldn't expect more than 65-70% attenuation with S-04. That would leave you with an expected FG in the neighborhood of 1028-1.032. My opinion, anyway.

 

[Donoroto]

If it is still doing things, let it. When it slows down, bump up the temperature 4-8 degrees F, again let it go for several days.

You can shake the fermenter a bit to rouse the yeast, some say it helps but it never has for me, the very few times I tried it.

Think of your underpitched batch as a huge starter. It will move slowly but eventually finish, taking a bit more time.

 

[Nberry]

If fermentation is still doing its thing, then wait a few more days and take another reading. I don't disagree however that technically you underpitched.
For an Imperial Stout, likely high in adjuncts, I wouldn't expect more than 65-70% attenuation with S-04. That would leave you with an expected FG in the neighborhood of 1028-1.032. My opinion, anyway.

Thanks. It has dropped to 1.048 so can I add more yeast to boost it back up?

 

[Nberry]

If it is still doing things, let it. When it slows down, bump up the temperature 4-8 degrees F, again let it go for several days.

You can shake the fermenter a bit to rouse the yeast, some say it helps but it never has for me, the very few times I tried it.

Think of your underpitched batch as a huge starter. It will move slowly but eventually finish, taking a bit more time.

Thanks. at the moment its 66 degrees so I should let it get to around 70 for a few days?

 

[Nberry]

The key is pitch rate. One pack could be just fine for a small batch, as the volume and gravity is increased the yeast volume increases. As temperature is reduced, the yeast volume is increased.

The general rule used by brewers to measure pitch rate million cells per milliliter per degree plato. Sounds complicated, be it pretty easy to figure out.
5 gallons = @ 19 liters
1.048 OG = @ 12 plato (divide gravity by 4 to get the approximate plato)

Ales are pitch at .75 million per ml/plato
High gravity ales at 1.0
Lagers at 1.5
High gravity lagers 2.0

So the calculations for an ale are: 19,000ml x 12 plato (1.048) x .75 million cells = 171 billion cells. Each pack of dry yeast contains between 110 to 180 billion cells depending on the source (I use 150 billion as a cell count), so it looks like one pack will do the job.

Your beer calculations would be 1.093 OG = 23.25 plato (actual is 22.2, but close enough), assuming it's 5 gallons and it's high gravity, the calculations are:

19,000ml x 23.5 x 1.0 = 441.75 billion cells or 3 to 4 packs of dry yeast.

Or you could use the Brewer's Friend yeast calculator:

https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

Thanks. I don't understand some of the verbiage, but I will eventually figure it out. I did the calculations for another beer I want to do and it's telling me to use 3 packets as the OG is 1.073. It's hard to get liquid yeast as I don't have a store anywhere close and it if mailed to me it's probably going to be hot by the time it arrives. I usually make a starter when I use liquid yeast but i haven't had a problem like this until now.

 

[Donoroto]

Thanks. at the moment its 66 degrees so I should let it get to around 70 for a few days?

Adding yeast now won’t make a difference. Don’t.

Letting the temperature rise a little will help. Do that, let it stay there until cold crash or packaging.

With yeast, you can use (x) packets or make an (x) liter starter. x being a number. You don’t need to buy that much yeast, growing your own is easy. Dry yeast is cheap enough to buy 3 or 4 packs though, and that is easier still. These days I rarely use liquid yeast, and certainly not in hot weather.

 

[HighVoltageMan!]

Thanks. I don't understand some of the verbiage, but I will eventually figure it out. I did the calculations for another beer I want to do and it's telling me to use 3 packets as the OG is 1.073. It's hard to get liquid yeast as I don't have a store anywhere close and it if mailed to me it's probably going to be hot by the time it arrives. I usually make a starter when I use liquid yeast but i haven't had a problem like this until now.

Unless you need liquid yeast, stick with dry yeast. It’s way easier and can get you great results.

 

[Ozarks Mountain Brewery]

if nothing works just add a tablespoon of sugar, see if they budge