Starter needed for 10 gal batch using yeast from 3 gal batch?

[aartdouglass]

I recently brewed an IPA:

Volume: 3.25 gal
Yeast: WLP001,1 pack
OG: 1.060
Temp: 68-72*F fermentation

I would like you reuse the yeast for a 10 gallon batch of a similar IPA with a similar OG. Using Mr Malty's pitching rate calculator I will need approximately 417 billion cells.

My Question: Does anyone know of a way to estimate the amount of yeast after fermentation if the volume and OG are known? This would let me know about how much yeast I'm collecting from the 3.25 gallon batch. This would help me know if I can just harvest/wash the yeast and pitch as is, or if I need to make a starter.

Thanks!

 

[aartdouglass]

Well, I just saw that that same calculator has a "repitching from slurry" option... so I can probably use that. I feel dumb.

However, still curious if there is a calculation for estimating yeast growth based on pitching rate, OG, temp, volume, etc.

 

[Schreiner]

Use this if you want to do calculate "steps":
http://www.yeastcalculator.com/

Or use the repitch from slurry tab in Mr. Malty.

Unfortunately, it's kind of an "educated" guess thing.

 

[SlitheryDee]

I suppose I would just treat the 3.25 gallon batch as a starter for the purposes of cell count calculation. According to yeast pitch, a 12 liter (almost 3.25 gal) starter from a vial of liquid yeast will net you 475 billion cells, which would seem to meet your requirements. If you're starting from a dry yeast packet you get 498 billion cells.

 

[flars]

I conservatively estimate 2 billion cells per milliliter for most harvested yeasts. Four billion cells per milliliter for WY 3711. I don't have any hop debris in my harvested yeast nor do I rinse the yeast poured from the fermentor.

You made a 3.25 gallon starter with a 1.060 wort. I estimated the yeast you used was 2 months old. If I'm using http://www.brewunited.com/yeast_calculator.php
correctly you have 28 billion cells to harvest. This number seems a bit high to me though. Harvest the yeast in a quart jar and estimate the volume after refrigerating for a few days. Follow this thread for more information.
https://www.homebrewtalk.com/showthread.php?t=579350