When you count yeast from a slurry do you sample from the thickest portion, or mix it all up and sample that?
Here is why I ask. I racked a Munich Helles yesterday in the middle of my Baltic Porter brew day. Originally, the helles was pitched at the proper rate of 1.5 million cells X 11.25 Plato X 23000ML of WLP830. The Helles is at FG, 1.010 from 1.045; 14 days into fermentation. My fermentation was picture perfect. 5 days at 49, krausen started to drop and I ramped to 60 for 5 days, then slowly reduced temperature to 50. The beer had cleared fairly well for this stage and there was a nice yeast cake on the bottom.
Here is the rub, I had about 2L of beer left after racking to a keg. I mixed together the slurry and the beer and poured into a sanitized gallon jug. I had 3.5L by volume. I mixed thoroughly and took 1ML of that mix and diluted it 10:1 to do a count. I hoped to determine how much slurry to pitch into my 6 gallon batch of 1.089 Baltic Porter. My count was 139 cells in 5 squars * 25 * 10,000 times my dilution of 10. This gives me 69 Million cells per ML of the original mixed slurry/beer. This seems pretty low. I had originally taken 1L of this and pitched it into the Baltic Porter after oxygenating. I realized that this was grossly underpitching, so I pitched the remainder of the yeast cake into the porter.
Each time I mixed the slurry, after a few minutes I saw a nice compact layer at the bottom. I'm not sure that my mixture is showing a true count of cell density. Hence the question above. Is it best to stick a pipet directly down into the bottom of the slurry and obtain the thickest part for counting?
I feel I made an error in not letting the yeast cake cold crash over night so I could decant the beer and get a better picture. Am I way off base? Is it possible that I only got 241 billion cells from the yeast cake? That seems incredibly low! I'm guessing my count was way off and I ended up over pitching. I'd rather do that then not pitch enough. Either way, it will make beer, hopefully good beer. Brew day went perfect until the yeast got involved.