Gotta say, this is a first for me, in 4 years of serious fishkeeping. I've only ever busted one heater before, and that was because I dropped it while moving some extra equipment around.
This one was still in my sump. I was doing a waterchange, and decided to clean out the chamber where the water enters the sump, which also contains the heaters. I turned off the power strip that the pumps are plugged into, but I forgot that the heaters are plugged into a different power strip
.I drained out the chamber, and everything seemed fine. i filled a bucket with water and started to pour it into the sump chamber, and BOOM! The damn thing exploded in my face! Scared the living bajeebus out of me as well.
Fortunately it was contained in a single chamber of the sump, and was relatively easy to clean up. I'm also lucky in that I have a backup heater that didn't break, so I'm not in emergency mode to find a new one.
So the lessen learned: ALWAYS check to make sure your heaters are unplugged before you drain the water below them....
