How much slurry should I pitch?

[brewtim]

Maybe this has been asked a few times, I'm not sure. I harvested around 400ml of slurry from a total amount of approx 1 litre from my latest brew last week (1.041), I have no way of counting yeast.

How much of the slurry should I pitch into my next brew (up to 1.060), I don't really want to over/under pitch?

Is there a way to calculate the amount iof yeast that might be in the slurry, I started with 180Bn cells?

:wha:

 

[Paddy]

I would be interested in knowing this myself as I will be harvesting some soon. i have seen people pitch yeast they have harvested and stored in a white labs sized vial and others from a standard size jam jar. I have also read it is a bad idea to pitch the entire cake as it contains too many dead cells. But perhaps someone more experienced can correct me if I'm wrong :)

 

[markmark]

This should be able to help - http://www.mrmalty.com/calc/calc.html

 

[brewtim]

This should be able to help - http://www.mrmalty.com/calc/calc.html

It helps a little but makes some assumptions (which is inevitable) that you know how many Bn cells per ml and what the non yeast percentage is.

I need 250bn cells requiring 130ml of slurry for a 23l batch when set on the standard settings, so I'll probably just go with 150ml and cross my fingers.

:thumb:

 

[godfrey]

use a small amount and make a starter :thumb:

I recently started a gallon of wine with a teaspoon from a frozen slurry

took 2 days to take off without a starter

but if you make a starter the yeast colony will double every few hours

so use a small quantity to make a pitch able colony :thumb:

 

[brewtim]

use a small amount and make a starter :thumb:

Thanks for the suggestion, I would make a starter if I needed to check viability (if the slurry was over a month old maybe), however I harvested the slurry only last Sunday and I'm brewing on Saturday so viability should be excellent. I'm really wondering what the pitching rate should be so that I try not to under or over pitch.

It's just a best guess effort without yeast counting (requiring a microscope etc). :pray:

On brewday the yeast will be roused with cooled wort and pitched with yeast-vit.