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Old 08-10-2010, 01:49 AM   #1
Feb 2007
Posts: 254
Liked 7 Times on 6 Posts

I'm making a starter using WLP820 Oktoberfest/Marzen. Because it's a lager, I'm opting to go the route of using two vials. However, each vial has different 'use by' dates (one is for September 3 and the other for November 11). Anyone have an idea as to what the viability for this starter in the Mr Malty yeast rate pitching calculator? I played with the dates and it certainly plays a pretty large role in the size of the starter.

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Old 08-10-2010, 01:56 AM   #2
Dec 2008
West Hartford
Posts: 351
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If it were me, I would do a 4 liter starter for that big of a lager and not worry about the production dates.

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Old 08-10-2010, 03:58 AM   #3
bsdx's Avatar
Apr 2010
Perry, Michigan
Posts: 328
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Since white labs tries to put an "expiration date" of 4 months after manufacture to come out to 50% viability, I would average the two. One is about 1 month old and the other 3 months old so I could tell the mrmalty calculator a date 2 months ago for figuring out a starter. It might not be scientific, but its also just a general guide.

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Old 08-11-2010, 08:58 AM   #4
If it's worth doing, it's worth overdoing
Jan 2008
Ridley Park, PA
Posts: 1,153
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Find the viability of each and add them. I got 75% for one and 27% for the other so you can assume 1 vial at 102% (production date is 4 months prior to date stamped on vial). Uncheck the "Calculate Viability from Date" and type in 102%. Move the growth factor slider until the "#Vials or packs needed with starter" shows 1. So for example, for a 5 gallon 1.054 lager starter on a stirplate, I get a 3 liter starter for your 2 vials.
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