Did you harvest by top cropping or from the bottom of the bucket?
When I top crop, I usually get a predominantly single color layer of yeast at the bottom of the jar of boiled, cooled washing/storage water. However, I have learned to follow the standard advice and wait long enough before top cropping, like 3rd day of fermentation, especially if a big beer, so I don’t remove too much yeast, especially if getting blowoff on a big beer. If you top crop you want to ensure you don’t remove so much yeast that the beer has a hard time to completely attenuate. But it is the best way to get just yeast.
There are trade-offs as to how you collect yeast. I know that a lot of guys who collect slurry rom the bottom of the bucket after racking off the beer, top it off with the washing water, refrigerate it, and don’t worry much about the amount of trub along with it when they rack new wort on top of it, without much of a problem. I would assume that this method does pose a higher risk of autolysis if leaving the second beer a long time in primary.
I don’t top crop if I use anti-foam drops, since there’s not much of a top layer of yeast.
I gave up yeast harvesting like this and now do the following:
Make my starters about 500ml larger than I need
Once fermented out on the stir plate I pour off the extra 500ml into a small, sanitized mason jar and place in fridge
Decant off clear beer
Take another smaller mason jar, fill half way with boiled water and cool and then pour slurry into it, label and fridge to store
Next time I plan on brewing I use this harvested yeast for the starter
I do this for all the regular strains I use and it works great, each batch of yeast comes directly from the starter and have saved jars as long as 6 months with no problems.
How many times have you rinsed this jar of yeast? I typically rinse at least twice trying to leave as much of the bottom dark layer behind. The lighter layer above is what you’re after. I also store the yeast after decanting. I’ve reused yeast like this after 6+ months refrigerated. The one time I didn’t decant before storeage I developed a small layer of mold on the top of the liquid.
Well, I pitched about 4 fluid ounces of the slurry (as per the mrmalty calculator) on Monday morning and the resulting fermentation was of usual vigor. I’ll check the gravity next weekend and see where I stand (OG was 1.077).
I harvesting from the bottom of the fermentor after racking into the serving keg.
Just once, then I crashed it and decanted the liquid before pitching.