Cell counting - anyone do it?

Howdy, I never was sure if I was under/over pitching my liquid strains, which I store on agar slants and grow up in the days before a brew. So I got a microscope and counting slide to count the cell numbers and use Mr Malty to check the numbers were correct.
Trouble is, with flocculent strains I find it impossible to get a reliable count as the slide I prepare seems to be nothing like the entire sample - the cell mass settles out visibly before I even get the pipette near it. Now I even doubt that less flocculent strains like weizen are being counted correctly. My numbers seem way way short of what should be there?
Anyone suffer this problem? I dont know if my microscopy skills are rubbish , or if I'm just crap at growing yeast :-(

I just started counting and use my pipette to mix the sample before I load the hemocytometer. I'll draw a ml then push it back into the sample container and continue to do so until it get it mixed. The first time I counted I came up with twice what I should have. I counted the other side and averaged them out. I was within a few billion cells of what was expected.

check this out: http://braukaiser.com/wiki/index.php?title=Microscope_use_in_brewing

and this: http://braukaiser.com/blog/blog/2012/10/03/yeast-un-flocculation-for-cell-counting/

Kai

Thanks Kai, I should know by now that the answers to all my brewing problems are usually found at braukaiser - your site makes me feel like a bit of a cheat though because you've done all the work which I just harvest as I need it.

Just one thing: I think I'll pour off the spent wort in future and add new fresh wort to un-floc. In your blog you mentioned that was the best way you tried before EDTA was available, did EDTA work as well as wort had done?

jat147 said:

Thanks Kai, I should know by now that the answers to all my brewing problems are usually found at braukaiser - your site makes me feel like a bit of a cheat though because you've done all the work which I just harvest as I need it.

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Thanks.

Just one thing: I think I'll pour off the spent wort in future and add new fresh wort to un-floc. In your blog you mentioned that was the best way you tried before EDTA was available, did EDTA work as well as wort had done?

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I have not tried EDTA since PBW, and most recently phosphoric acid, works well enough for me.

For most practical brewing applications, where you want to check the amount of yeast gown and while planning to use the yeast, I think wort works the best.

I had a case where wort was able to beak the yeast up into small enough particles that I could draw a representative sample with a pipet but where cells still formed many small clumps. In that case you can add PBW or phosphoric acid to the water you are using for sample dilution.

I remember WoodlandBrew mentioning that vinegar also works well.

Kai