Complicated yeast starter question

[Johnnyboy1012]

Brewing a German Pils in a few days and building up a yeast starter with WLP 830. I put one fresh vial in a 2L starter on a stir plate. It is in the fridge now to get decanted and put into another starter. I don't know what size starter to use next. Mrmalty says I need 378 billion cells. From my understanding putting one fresh vial into a 2L starter will double it so I have about 2 billions cells aka 2 vials of yeast in my flask. Here's my question: according to mrmalty I would need to pitch 2 vials of yeast into a 1.75L starter to get me to 378 billion cells. But in the yeast book there is a chart that says if I do a step starter pitching my decanted 2L starter into fresh 2L of wort will only get me to 300 billion cells because of diminishing returns. This make sense to anyone?

 

[shivalotus]

You might try using yeastcalc. They are setup to do stepped starters.

 

[JFK]

yea I would go use yeastcalc as well and you will get some diminishing returns but if you repitch your yeast into a second 2000mL starter I would think you should be in the ballpark of what you need and if not you decant it off and do it a third time. Whenever you need a multiple step starter yeast calc is far better than mr malty.

 

[Johnnyboy1012]

so I put my numbers into yeastcalc and after playing around with it I found that the Kai Stir Plate tells me that by pitching one vial into 2L, I have 382 billions cells which is close enough to the 378 it says I need. That means I do not have to decant and make into a new starter but the Jamil stir plate tells me that I only end up with 271 billion cells and need to make another starter. I like how Kai posts his experiments and how he came about getting his numbers for yeast growth when using a stir plate. I have always used Jamil's method but I did not know that his info was estimated when using a stir plate. What do you suggest?

 

[JFK]

Id go with kai since he has posted his methods and you know it's leads estimated.