I am brewing a Munich Helles this weekend and I only was able to get 1 Wyeast pack of Munich lager. According to a pitching rate calculator, I would need a 4L starter on the stir plate based on the package date of the yeast. I only have a 2L flask. I want to step it up once, but I don't know how much volume for each step. Perhaps it is just a 2L starter into another 2L starter after it ferments out?