Original post by: portervill ,
DEFINITELY DON'T USE LEMON JUICE. My Barista manual recommends a product designed for the machines, a citric acid, OR pulp-free lemon juice. I used bottled lemon juice, and before I could finish the descaling process, the machine kicked out the GFI switch on any outlet I plugged it into (and still continues to a day and a half later). One of the questions on this site addressed that problem--I followed all the suggestions, but the machine is damaged.