Yeast washing and reusing

[Grreg2]

I have been watching videos on washing yeast. My question is about reusing the washed yeast. How are you supposed to know how many cells you have? Is it safe to assume that if you make a 1-2 L starter prior to re pitching you will have the proper pitch rate? What if this causes you to over pitch?

 

[LLBeanJ]

There's no need to wash yeast. Ever. Instead, buy some new yeast, make a somewhat larger starter than needed and save some off for a future starter, while pitching the rest in your current brew. Brewing two batches in a row that use the same yeast? Direct pitch yeast from the first batch's fermenter into the second batch. No need to wash it.

As far as cell counts, there are online calculators that will get you in the ball park. And ball park is close enough. Once you make a few starters and save off a known amount (based on cell counts from a yeast calculator) into a mason jar or similar container, you'll find it's relatively easy to guestimate cell count, and if you have a rough cell count and viability date, you can use a calculator to plan your next starter. Also, I wouldn't worry too much about overpitching.

Here are a couple of good yeast calculators:

http://www.yeastcalculator.com/

http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/