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01-13-2014, 11:28 AM   #1
mtnagel
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 Can someone explain the calculations on Mr Malty's Repitching from Slurry Calculator

Link to Mr Malty's calculator. Select repitching from slurry tab.

Let's start with 1.080 OG, 5.25 gal batch, uncheck "Calculate viability from date" and enter 90% in the box.

We should all have 287 billion cells needed, which I understand.

To get the number of ml of yeast slurry needed, what I would do is start with the yeast concentration. The default is 2.4 billion/ml. I would then multiply that by the % yeast. To get that, we have to take the "non-yeast %" and subtract it from 100%, so that's 100% - 15% = 85%.

So 2.4 billion/ml x 0.85 = 2.04 billion/ml. I would then multiply that by the viability, 90%.

So 2.04 billion/ml x 0.9 = 1.836 billions/ml.

If I need 287 billion cells, I would take the 287 and divide it by the 1.836, to get 156.3 ml of that slurry needed.

But Mr Malty says I need 147 ml. Now I know that's not that different considering we are using approximations on approximations, but I just don't see how he came up with his math so I wondering if I'm missing something simple.
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01-13-2014, 07:04 PM   #2
eluterio
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Good question I have no clue but hopefully someone does..

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01-14-2014, 02:52 AM   #3
mtnagel
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Maybe I should try to contact Jamil.

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01-16-2014, 12:32 PM   #4
mtnagel
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I facebook messaged him and emailed him and no response. I'll update if I do get a response, but I assume it's not coming.

Until then, I'll use my own calculations because no one has said I'm wrong and it makes sense to me.

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