I brewed a 5.2% porter using WLP007. Half a Protafloc tablet near end of boil. After bottling I swirled bucket with about 2.5.litres of cooled boiled water.
This is what it looks like.
I can't perceive what is healthy yeast. Should I just bin it and buy another pack of yeast?
Put it in the fridge and let it settle a bit, after a few hours (maybe 12) or so you should eventually see layers, with a cream colored cake on the bottom which will be your yeast. It's a little tricker with darker beers as the colors seem to be closer together.
While IMO you'll always be better off using a fresh pitch (+ starter) to make sure you've got healthy yeast, harvesting yeast typically does work well and saves you the ~8USD for the WLP. I usually recommend to harvest off more neutral beers, or use the washed yeast on a similar profile beer.
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