I have a Belgian Pale Ale in my fermenter that is three weeks old. Is it too late to pitch a big brew right on top of the cake?
No, it should be fine.
I just pitched yeast slurry from a batch that had been in primary for three weeks into a new batch this past Saturday. It took off in about 10 hours and is at high krausen 40 hour later…
Similar question, but my very first batch was a Belgian Wit, and went over like gangbusters, so I have had several people ask me to brew them each a batch. Can I brew a batch, have it sit in primary for 2 weeks, rack to secondary, and then brew a new batch of the same kit right back onto the original cake? Will I still need to pitch again?
I do that all the time, works great! It’s one of the good reasons to use a secondary. You really only need about half the yeast cake, though, so maybe scoop some out and store it in the fridge or dump it. At a point the trub starts taking up a lot of volume in the bottom of your fermenter.
For repitching into the same OG beer, about 1/3 the yeast cake is the right amount. Or maybe that works for me because I harvest yeast straight from the primary.