• Welcome to the new forum! We upgraded our forum software with a host of new boards, capabilities and features. It is also more secure.
    Jump in and join the conversation! You can learn more about the upgrade and new features here.

Pitching Rate Calculation Error

Ghosttrain

Apprentice
Joined
Dec 18, 2011
Messages
10
Reaction score
0
Location
Lynchburg VA
Reposted from the brewing discussion forum since there may be an issue in the Beersmith yeast calculation that needs to be investigated.

Using the Yeast Starter Tool for a 5.25 Gallon batch with an OG of 1.067 both BS2 and MrMalty calculate ~242 Billion Cells. 
Using Liquid Yeast packaged on 11/6/2011 both tools estimate ~67% Viability. 

Now when you get to the calculation for the size of the starter in BS2 without a stirplate the internal calculation of the number of packs needed without a starter appears to be incorrect.    With the above inputs BS2 suggests that 6 yeast packs are needed which it 2 times as much as is really needed

6 packs x 67 Billion cells / Pack = 402 Billion cells

The ideal pitching rate is 242 Billion cells. 

The calculation then suggests that 2 vials in a 3.09 Liter starter is required which is about 1 L more than necessary to achieve a 1.86 growth factor.

Would you take a look at the internal calculations in BS2?    If there is a conversion factor error or an incorrect table lookup that could impact the calculation of the starter size needed with a Stir Plate.

Cheers
 
I agree:  I use a Stir Plate and the difference between Mr Malty and BS2 is HUGE.    I know that Brad posted he was going to talk to Jamil about this earlier?

It seems like the Growth Factor is perhaps the difference between both; I'm not even sure what the Real Growth Factor is for Yeast on a Stir plate.  2.66? or what?
 
Are you talking about the yeast starter tool in the recipe or from the tool tab?
I found the one from the tool tab seems to be very close to MrMalty. It's the in recipe one that is way off.
 
Back
Top