Estimating cell counts of slurry

Does anyone have a practical method? I've seen some posts that refer to 1B:1ml. That seems reasonable. Thoughts? THANKS

You can use yeast calculators like Mr.Malty. You put the date you harvested the slurry and it estimates how many billion based on that date.

I found this page from Wyeast very helpful.

http://www.wyeastlab.com/hb_pitchrates.cfm

At the bottom of the page there are some tubes with 10%-60% yeast slurry with the estimate of yeast/ml, so the 40% yeast slurry has 1x10^9 or one billion yeast/ 1 ml. A good way to do this at home is to get some 50ml graduated tubes (you can get breast milk storage tubes at Target they work great), mix up your slurry so all the yeast and in suspension and add fill the 50ml tube to the 50ml mark. loosely cap the tube and stick it in the fridge and wait for all the yeast to settle out from the liquid. then you can estimate the % yeast in the slurry and infer a yeast count. Then devide this by the amount of yeast you need to determin the ml of slurry you will need to get to your desired pitching rate.

Thanks!

Not a fan of the Mr. Malty calculator since I get outrageous figures from it. The wyeast site has some good info but is still rather alarmist. IE- Double pitching rate for homebrew setting and not to repitch slurry over 2 weeks old...

I'm reading the yeast book by Chris White (i believe owner of WL), and from what I can tell the only way to really know what is up with your slurry is to stick it under a microscope.

zwiller said:

Thanks!

Not a fan of the Mr. Malty calculator since I get outrageous figures from it. The wyeast site has some good info but is still rather alarmist. IE- Double pitching rate for homebrew setting and not to repitch slurry over 2 weeks old...

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Are you just discounting things merely because you don't "like" the answers? Hope you don't do that in real life or at work...

Check out this older thread in which Biobrewer puts out an easy method for counting slurry:

https://www.homebrewtalk.com/f163/estimating-cell-count-334105/

rpe290 said:

Are you just discounting things merely because you don't "like" the answers? Hope you don't do that in real life or at work...

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No, I discount things which are contrary to my experience...

I agree that counting the cells on a hemocytometer using a microscope is the only way to know for sure, but for the most part 1 billion cells per ml of settled slury will get you close enough.

I've found from cell counts that Mr. Malty's viability by date can be way off.

See here for details:
http://www.woodlandbrew.com/2012/11/counting-cells.html

WoodlandBrew said:

I agree that counting the cells on a hemocytometer using a microscope is the only way to know for sure, but for the most part 1 billion cells per ml of settled slury will get you close enough.

I've found from cell counts that Mr. Malty's viability by date can be way off.

See here for details:
http://www.woodlandbrew.com/2012/11/counting-cells.html

Click to expand...

In your blog you ask for duplication, which has been done by Kai Troester and the data added to yeastcalc as an alternative for estimating cell counts.

http://braukaiser.com/blog/blog/2012/11/03/estimating-yeast-growth/

Starting to have some clarity now with YeastCalc's viability and Kai's growth rate. Also, I think I understand why slurry is not the preferred method to use as it is harder to estimate than just using a new packet/vial. That said, biobrewer's method seems sound.