[Steve L]

I'm sitting on a 90ml slurry of WLP001 that is about 5 weeks old. Mrmalty has my viability at about 36-40%. I'm curious as to others opinions for their cutoff on for viablility in repitching yeast.
Specifically, I'm brewing a 2.5 gallon batch of a 1.068 IPA that needs about 117 billion cells. At the viability that MRMALTY has me at I'm looking at needing 154ml of slurry. I could do a 2 liter starter I suppose.

Looking for opinions from the repitchers

Thanks,
Stevo

[beersk]

I'd do a 1 qt starter for that. Should give you plenty. I usually will wait a month before I start making starters with slurry since I usually split the yeast cake up between 2 or 3 jars.

[a10t2]

MrMalty is really conservative with its viability formula. Assuming the yeast has been refrigerated the entire time, it's probably more like 60-70%. So 90 mL of packed slurry would be around 150-200 billion viable cells.

[ynotbrusum]

I assume half the slurry for lagers and 1/3rd of the slurry for ales after 30 days from original pitch .  Just based on experience - nothing scientific.