Yeast Starter Calculations.. Right or Wrong?

[pod_021]

Hey guys i'm looking to make a 1.052 gravity hybrid beer and these are the calculations i have...

Cells Needed:
0.948 bil/gal-point for a hybrid beer..
5 Gallon batch ( 20l )
1.052 ( 52 gravity points )

.948 X 5 X 52 = 246.48b cells needed?

Viability: i'm guessing is 80b cells

Growth Rate Needed: 246.48/80 = 3.081

Innoculation Rate: Using this graph:

Growth rate of 3.081 Innoculation rate 25mil/ml

Yeast starter size:Viable cells 80b / innoculation rate 25 = 3.2L starter

Does this sound correct to ye guys for a 5.2 ABV beer?

 

[maida7]

try using the calculator on mrmalty.com

 

[Kaiser]

Are you using a stir plate?

With a stir plate I don't think you need a 3+ L starter. Based on this calculator (http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/), which has a model based on my research I think you are fine with a ~1.5 L starter.

Kai

 

[pod_021]

Thanks guys, I don't own a stir plate but do you think a 1.5l would still be suffice?

 

[sherma]

Thanks guys, I don't own a stir plate but do you think a 1.5l would still be suffice?

Here is another calculator that I like. http://www.yeastcalc.com According to it, you need a 2.2 liter starter, if you do intermittent shaking.

 

[maida7]

Thanks guys, I don't own a stir plate but do you think a 1.5l would still be suffice?

no, without the stirplate, the starter should be bigger. I calculate a 3.7L starter is needed if no stirplate or oxygenation is used.

but... If you can only make a 1.5L starter and you have no stirplate that's not the end of the world. It's not going to be pitching at the recommended pitching rate but it will still make beer and it will be better than if you had made no starter at all.

A third option is to make a 1.5L starter and then decant that and pitch it into a second 1.5L starter. This takes more time but it will get you to the proper pitching rates.

A forth option is to buy some more tubes of yeast. 2 vials into a 1.5L starter will get you there.

 

[pod_021]

Great stuff guys thanks, and I take it the OG of the starter will also be key? Looking or a 5.2ABV beer

 

[Kaiser]

yes, w/o stir plate you'll need more wort.

Kai