Spike Brewing 12.5 Conical Fermenter Giveaway - Enter Now!

Home Brew Forums > Home Brewing Beer > Fermentation & Yeast > Can someone explain the calculations on Mr Malty's Repitching from Slurry Calculator

Reply
 
LinkBack Thread Tools
Old 01-13-2014, 11:28 AM   #1
mtnagel
HBT_LIFETIMESUPPORTER.png
Feedback Score: 6 reviews
Recipes 
 
Join Date: Apr 2012
Location: Cincinnati, Ohio
Posts: 1,948
Liked 178 Times on 139 Posts
Likes Given: 164

Default 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.
__________________
-Matt
mtnagel is offline
 
Reply With Quote Quick reply to this message
Old 01-13-2014, 07:04 PM   #2
eluterio
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jun 2012
Posts: 489
Liked 18 Times on 18 Posts
Likes Given: 69

Default

Good question I have no clue but hopefully someone does..

__________________
eluterio is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2014, 02:52 AM   #3
mtnagel
HBT_LIFETIMESUPPORTER.png
Feedback Score: 6 reviews
Recipes 
 
Join Date: Apr 2012
Location: Cincinnati, Ohio
Posts: 1,948
Liked 178 Times on 139 Posts
Likes Given: 164

Default

Maybe I should try to contact Jamil.

__________________
-Matt
mtnagel is offline
 
Reply With Quote Quick reply to this message
Old 01-16-2014, 12:32 PM   #4
mtnagel
HBT_LIFETIMESUPPORTER.png
Feedback Score: 6 reviews
Recipes 
 
Join Date: Apr 2012
Location: Cincinnati, Ohio
Posts: 1,948
Liked 178 Times on 139 Posts
Likes Given: 164

Default

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.

__________________
-Matt
mtnagel is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Repitching yeast slurry NunoAraujo Beginners Beer Brewing Forum 9 11-08-2013 02:15 AM
Repitching yeast from slurry motoed Fermentation & Yeast 4 02-21-2013 01:16 AM
Repitching slurry - volumes? Graeme Fermentation & Yeast 18 09-28-2011 06:46 PM
Repitching a Slurry for 1.070 OG batch DannPM Fermentation & Yeast 3 02-16-2011 01:01 AM
repitching on slurry Zooom101 Fermentation & Yeast 14 02-24-2010 04:12 AM