How much harvested Yeast to use

[Over The Cliff Brewing]

I'm going to help my father-in-law brew an dry irish stout on saturday. His yeast Wyeast 1084 is dated 3/12/2021. Not sure if this is still viable. Instead I plan to sub that out with some Nottingham from my jar. Should I make a starter with all of it or some portion of it? I normally just dump whatever is in the jar into the wort and let it rip. We'll be brewing 5 gallons (extract).

 

[Donoroto]

The recipe builder has a yeast category 'slurry' which offers accurate numbers. But overpitch (i.e., the whole jar) couldn't hurt. Maybe a cup of slurry as a guess??

Your FIL can try a starter - get it going tonight! - and see if his old pack might be viable. A 1 to 2 liter starter using almost any kind of wort (ideally some DME) would do.

 

[Over The Cliff Brewing]

I used 1/2 approx 3/4 cup in a 2L starter this morning. Well see what it looks like tomorrow. Push come to shove, I'll buy some yeast before we brew.

 

[J A]

Slurry has the same shelf life as new yeast. If it's just a couple of weeks old it has high cell count and as little as a cup would be plenty for 5 gallons. If it's a couple of months old, probably at least a pint needed. At 4 months, you could probably still trust fermentation from about a liter. At 6 months or more, I wouldn't trust it and would be making a starter.

 

[Over The Cliff Brewing]

It's about 1 month old

 

[Donoroto]

So have a pack of S04 or US05 on hand for just in case, but your starter will take off, trust me.

 

[Ward Chillington]

For 5 gals I would have gone with more but that would have been kveik..I over kill compared to the masters...keep us updated!

 

[Yooper]

The yeast calculator does have the input and calculation for slurry and the amount to pitch. I use that.

 

[J A]

It's about 1 month old

If you're making a 2 liter starter with 3/4 cup of 1 month old slurry, you'll have a pretty huge cell count. I predict you'll have an extremely vigorous fermentation. Keep an eye on the temp and keep it on the cool side so it doesn't go insane and heat up. With Nottingham, you could be at gravity in just a couple of days.

 

[Over The Cliff Brewing]

If you're making a 2 liter starter with 3/4 cup of 1 month old slurry, you'll have a pretty huge cell count. I predict you'll have an extremely vigorous fermentation. Keep an eye on the temp and keep it on the cool side so it doesn't go insane and heat up. With Nottingham, you could be at gravity in just a couple of days.

Notty can be pretty robust when fermenting. I'm going to insist on a blow off tube instead of an airlock. This is my father-in laws 3rd beer so he is still an ultra beginner.

 

[J A]

Notty can be pretty robust when fermenting. I'm going to insist on a blow off tube instead of an airlock. This is my father-in laws 3rd beer so he is still an ultra beginner.

Definitely!! Temperature will be a real key, as well. If it's possible to keep the temp in the low 60s to start, it should slow things down enough to avoid the worst of the potential blow-off worries.

 

[Over The Cliff Brewing]

There was vigorous activity less than 12 hours after pitching on Saturday afternoon. As of last night I was told the activity has slowed but still working. I'd say that the Notty yeast starter is doing it's job. We'll see what FG is in a few days.