Almost the same thing happened when I was in Iceland... frantic roommate phone call saying the pump was running dry and topping up wouldnt help.
I got him to turn off the return and put a hang on skimmer i had. Came home to lots of algae outbreaks and the display filled with heaters and hoses, but no flood at least.
Sorry to hear about the flood, roommates need tank training days. At least with your parents around you have some extra hands to help out with the cleanup!
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