Wash yeast or just use as is?

Here's the situation: Brewing the next two weekends, using the same yeast strain. I have 2 conicals, normally dump yeast/trub after first week, then just before kegging. I've never washed/reused yeast before (just been lazy I suppose). Should I just dump the trub/etc after the first week and pitch that directly, or should I wash it first, or will there even be enough yeast dropped out after the first week to re-pitch? Just figured this was a good opportunity to re-use, although the second batch is for a competition, so I don't want to screw it up!

Craig

There will certainly be enough yeast to pitch, but the question is whether it's the right kind of yeast. Harvesting yeast too early will lead to selective pressure towards early flocculating yeast and against late flocculating yeast. I don't know how much difference this will necessarily make in a single cycle, but do it a few times and you'll end up with a very different yeast than you started with.

It is an interesting experiment, but if I were trying to make something for competition I would probably stick to what I know works. I would also definitely wash the yeast to get a known quantity of clean healthy yeast, but many people are much more casual about it than that and seem to be happy with their results. I would say that late, careful harvesting and good washing are both "best practices", but whether or not it will make a significant difference is an open question