For the past three years I have been chilling my wort with a whirlpool immersion chiller (http://www.morebeer.com/products/wort-chiller-immersion-recirculation-arm-50-12.html) and a pump. It chills very fast and it is easy enough to clean and sanitize, but I also bought it because of the purported benefits of a hop whirlpool. After some trial and error, I have been doing a hop stand by replacing my flame-out hops with whirlpool hops that I add after chilling the wort to just under 180F, at which point I add the whirlpool hops and let stand for 10-30 min, then chill again. This has been effective, but frankly I still got better late-hop aroma from my flameout hops when I had a simple immersion chiller that took 2-4 hours (and a small lake’s worth of precious Californian water) to chill my wort down to near-pitching temps.
I was wondering what other people who use a pump to whirlpool and hop stand do. Do you chill down partially before adding the hop charge? Do you add flameout hops as well as whirlpool hops? Do you give it a longer hop stand? A shorter hop stand?