I'm pretty sure the grind was the culprit. I think it was too fine.
Definitely coarsen up the grind a lot. When doing a 4 minute plus extraction, it is very easy to overextract, but you know that.
![Wink ;)](https://www.greencoffeebuyingclub.com/Smileys/default/wink.gif)
Also when doing a 4 minute extraction you get more hemi cellulose hydrolysis. This produces more reducing sugars, primarily xylose, which is not sweet (as most sugars are not sweet), but lends a silkier, creamier mouthfeel.
I'm going to have to be taken off the roadshow list, I jumped the gun and bought one...and it arrived today. Did 3 trial runs after calibrating it and running a cleaning cycle. No problems whatsoever with too large a bloom. All coffee was 3 day post roast with a city( ethiopia chelelektu, SM's), city+( sidamo bonko, last years shrub offering), and full city roast levels ( Guat Atitlan, Klatch). The chelelektu was extracted at 200F( 64 grams), the bonko at 202F (66 grams), the guat at 201F(66 grams). All coffee was delicious.
Thanks Joe! I really like this brewer!!!