I have a conical fermenter, but I haven't yet attempted to harvest and wash yeast. I typically dump a little from the bottom every few days once fermentation starts, primarily so that there isn't too much sludge which makes things hard to drain out of the bottom valve. Once fermentation has appeared to have completed, I try to dump all that has collected in the bottom and let it sit another week or so (so, this is like my secondary).
Once keg the beer, there is still a fairly good amount of trub in the bottom of the conical.
My question is, when do I collect yeast? Every time I'm dumping out of the bottom valve, it's yeast correct?