Deebo wrote:This is interesting, in short, this could be a temperature issue? I generally flush for 2-3 seconds after the "dance"... the recommendation would be to shorten this? I really hate the aesthetic of eric's thermometer, which is why I never got one, but I wonder if the cheaper one would help me figure out a better flushing routine.
I'm at 5000 ft here in Albuquerque, and have found that I need to stop very soon after the end of the water dance. If I were to stop according to total flush volume, or by grouphead thermometer reading , the altitude wouldn't make much difference, but the end of the water dance of course would be expected to happen later and at a cooler temp. I generally stop the cooling flush right about the time I hear it subside on my Giotto Evo for a flush-and-go. Try some shorter flushes to see if the taste improves, but don't expect that to reduce your bubbles.
I had the same reservation about the appearance of the EricS grouphead thermometer but got over that and am glad I did. For flush-and-go from an idle machine I could work fine without it, but for subsequent shots, for learning about the machine, and for knowing right away when I have a stalled thermosyphon it has proved indispensable.
There seems to be general consensus that giving roasts a long rest is a good idea at altitude - ask at the shops there in Denver that you like - they may be resting their beans longer than you do. Here's a topic with some good posts about that: Espresso at altitude - Could use some theory
. Also see this post - About Roasting and Brewing at Altitude
from an experienced home roaster and barista (Martin) who moved from New York to Santa Fe. Note that he had the bubbles, but found it best to ignore them.