General Homebrew Discussion / Re: What was your last change in your procedure that you feel was beneficial?« on: August 27, 2012, 05:59:11 AM »
But I just thought of something I might try next time:
Use a hose to blow the O2 under the wort surface. This should create foam. Once the foam reaches the carboy neck the the air has been purged out and I'll close the carboy and start shaking. The O2 dissolved in the wort should depend on the head space to wort volume ratio and the wort temp. I'm using 5 gal carboys, so this may not be as practical for 6 gal carboys due to the larger head space and possible over-oxygenation.
I did some math on this and with a head space of 1.5 l and 17.5 beer volume, which is a pretty small head space, you'll end up with about 25 ppm DO. This is for filling the head space with O2 and shaking until so much O2 dissolved that the head space pressure is too low to push more O2 into the wort.
25 ppm oxygen may be good for a high gravity beer, but is way too much for normal beers. So the technique of purging the head space with O2 by creating foam with the O2 is not all that practical.
But isn't it unlikely that you'd get all that O2 into the wort anyway?