Do I need more yeast for my Imperial Stout?

Did not check the mr malty yeast calculator, so I bought 2 vials of WLP001 and made a 5 liter starter, but according to the mr malty calculator I need 3 vials.

What can I do to have enough yeast. Brewing tomorrow. Buy more vials?

Style: Imperial Stout OG: 1.097
Type: All Grain FG: 1.022
Rating: 0.0 ABV: 9.83 %
Calories: 316 IBU's: 62.32
Efficiency: 85 % Boil Size: 13.17 Gal
Color: 56.0 SRM Batch Size: 12.00 Gal
Boil Time: 90 minutes

Grains & Adjuncts
Amount Percentage Name Time Gravity
30.00 lbs 78.43 % Fawcett Maris Otter Pale Malt 75 mins 1.038
1.75 lbs 4.58 % Chocolate Malt 75 mins 1.028
2.50 lbs 6.54 % Roasted Barley 75 mins 1.025
1.00 lbs 2.61 % Caramunich Malt 75 mins 1.033
2.00 lbs 5.23 % Special B Malt 75 mins 1.030
1.00 lbs 2.61 % Black (Patent) Malt 75 mins 1.025

When did you make the yeast starter? You may need another vial of yeast depending on when you made the starter.

Started it yesterday, on a stir plate.

Really, the point of a starter is to remove the necesity for more vials...with the added bonus of making sure your yeast are alive, healthy and ready for the glutanous meal infront of them.

Espiecially if you are using a stir plate I don't see any need to pitch more vials unless your yeast are failing to taking off in the starter.

Germelli1 said:

Really, the point of a starter is to remove the necesity for more vials...with the added bonus of making sure your yeast are alive, healthy and ready for the glutanous meal infront of them.

Espiecially if you are using a stir plate I don't see any need to pitch more vials unless your yeast are failing to taking off in the starter.

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There may be a need for more vials if the starter wasn't given enough time to reproduce the required amount of yeast.

Seven said:

There may be a need for more vials if the starter wasn't given enough time to reproduce the required amount of yeast.

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Agreed, but even then he would have to delay his brew day...I don't think a vial could go from store fridge to active fermention in a starter in 16 hours...at least not enough to impact the cell count of the starter largely. But I could be wrong!

hinke said:

Started it yesterday, on a stir plate.

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Since you started it yesterday and you're using a stir plate you *should* be OK, assuming the yeast are healthy and they have been given enough time to finish reproducing.

Just out of curiosity, what sort of a container did you use to make a 5L starter using a stir plate?

I used an Erlenmeyer flask. The thing was bubbling this morning with some foam on top. Usually it does not produce much kreusen when using the stir plate.

I use 100grams/liter of light DME.

I could go and buy 2 vials, and just dump them in when dumping the rest of the yeast.

When I plug your numbers into Brewzor, looks like you're pretty close. It puts you at 580 billion, you should be more like 790 billion. You'd only need to add a little more wort to get you up to where you should be. It says a single stage starter should be around 8 liters. Not severely underpitching where you are though.

I just realized your batch size is 12 gals. This changes things since Mr. Malty says you'll need 792 billion yeast cells.

So, maybe I need 2 vials more then. 100 billion each right? Just want to make sure I don't mess this up. I can spend more on it, I do bulk buy on grains and save money that way.

I should have planned the yeast better, I was so focused on the grain bill. I normally start a smaller starter and step it up over a week or so.

I don't know how to calculate what 2 vials of yeast in a 5L starter will produce on a stir plate. Assuming that your starter will at least double the starting cell count to 400 billion, then you'll still have a deficit of 392 billion cells. That's almost 4 more vials of yeast needed (in addition to your starter) but I'm sure if you only bought 2 or 3 more vials and pitched them along with the yeast starter then you will be fine.

Sorry about missing your intended batch size earlier.

Hmm. Maybe I'll push my brew day forward one day, and create another starter. I'll think about it.

maybe just brew a smaller beer then use the yeast cake for your RIS. I always start a new yeast with something like scottish ale or mild then move to big beers with the yeast cake.

ETA: with a 5L starter your 20% to a 5 gallon batch

King of Cascade said:

ETA: with a 5L starter your 20% to a 5 gallon batch

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Good point, unless you decant, then you are starting to tilt the tables from proper cell count, to realistic needs. Mr. Malty is good to calculate smaller beers, but I have a tough time believing their numbers for big beers.

Plus I never decant starters. The ones in suspension are the ones I want in my beer!

I'd just use the starter you got and pitch a pack of S-05 with it, that should get you the rest of the way there

Normally I chill my starters the night before, then decant most of the liquid. But Don't think I'll do that this time.