Sorry to hear that...that's awful.
Just a theory...
Shutting the skimmer off at night allowed the oxygen level in the tank to drop to deadly-low. Fish died....then the skimmer came back on to find a extra jolt of death in the water and foamed over.
Skimmers supply O2 to the water as well as remove nastiness. This is critically important at night when no photosynthesis is occuring. (unless you have an opposite-light-cycle refugium...which can help)
Once you are up to it, read this...
http://reefkeeping.com/issues/2005-08/eb/index.php
__________________
400 gal reef. Established April, 2007. 3 Sequence Dart, RM12-4 skimmer, 2 x OM4Ways, Yellow Tang, Maroon Clown (pair), Blonde Naso Tang, Vlamingi Tang, Foxface Rabbit, Unicorn Tang, 2 Pakistani Butterflies and a few coral gobies
My Tank:
http://www.canreef.com/vbulletin/showthread.php?t=28436