Beer Forum

Greetings,

I switch between White Labs and Wyeast depending upon what yeast strain I need and what is available at each of the two LHBS near me. The retailer that carries Wyeast only stocks Propagator packs (25 billion cells). I know that JZ's pitching calc for liquid yeast is designed around White Labs vials and Wyeast Activator cell counts. So, my question is how can determine the amount of start wort I need when I'm using the Propagator packs (which have 25% of the cells of the Activator/Vial)? Thanks!

Well I would look at the total amount of cells needed for you OG brew. Then realize that a 2-liter starter should get your cell count to the point where you could innoculate up to 1.060 OG wort (5 gals). So if you are doing a standard ale, then 1 pack of propogator in a 2-liter starter should do the trick.
What I would try, is do a 1 liter starter, then after the krausen starts to fall, add another 1 liter. That may give you more cells.
Or you could just use 4 propagator packs for each Activator pack needed in calculating your starter. Or you could double the starter size needed for the activator and then use 2 propogators.
Either way if you are making a standard size OG beer, any of these options should give you enough yeast.
Here's some more resources:

http://www.wyeastlab.com/hb_productdeta ... roductID=2
http://www.mrmalty.com/starter_faq.htm

Cheers!

When I use the propagator packs I usually do a 2000 mL on a stir plate. When it finishes I'll seal it up and crash it in the fridge for a day. I'll then decant the liquid and add another 2000 mL starter to it.