I was going to wash my yeast and re-use it for my next brew. And as I'm transfering to my seconday it occured to me that the krausen left over in my primary should be all yeast. So just sanitized a spoon and scraped it off the side of the bucket and into my mason jar full of water. Is this a good idea or a bad idea? Am I right in assuming this is yeast up there or is this just trub?