Me wants yeast!

[Beer-lord]

Planning on doing a Dr. Hoptagon semi clone on Sunday---yeah I know, tis not the season for dark and heavy beers but I like em (hey, don't judge). So, as my 007 is getting a bit old, I'm making a 1.5 liter starter for Hoptagon and a 1 liter to store. I only have 1 stir plate so I'm going to see how the small one does without one and wink and shake it as I pass by it.
Should be ok.

photo.JPG (290.62 KiB) Viewed 446 times

[ScrewyBrewer]

I calculate 10% viable cell lose per month for refrigerated yeast, it's a best guestimate no science behind it at all. So after six or eight months in storage I'll make a two liter 1.020 gravity starter and pour a stored vial of that yeast into it with a bit of nutrient and let it spin until the krausen falls. Then later on I'll use this freshened up starter with it's built up cell count to make another starter I pitch in the fermentor. Doing it this way I've managed to ferment beer using yeast that was in the back of my refrigerator for nearly a year.

[Beer-lord]

This yeast was from a beer I brewed in last December and there was a lot in the jar so I used it all in a 1.039 starter. The smaller jar is another vial of yeast that I made in case the 1.5 liter starter wasn't enough. yeastcalc and mrmalty only call for a 1.2 liter starter for the beer I'm brewing so I think I'm ok with 1.5 l on this beer.

[ScrewyBrewer]

Yep that's pretty much similar to how I do it too although my approach varies a little from what you've described. I enter my recipe's estimated OG and FG it's batch size to be fermented and select whether it's an ale or lager yeast. Example: OG = 1.048, FG = 1.010 and a five gallon batch needs about 175 billion cells of ale yeast to get 77% attenuation.

I know from experience that a 100 billion cell vial of yeast will produce a bit more than 220 billion cells in a two liter starter spun on a stir plate, which is close enough for me since I prefer to err on the high side anyway. In the end it comes down to having enough viable cells to get the job of fermentation done quickly and cleanly.