I wasn't able to finish my post properly yesterday so...
I'm not saying that I know what went wrong with your corals, but I don't think that lighting was the problem either.
There was an article in Advanced Aquarist that demonstrated how the lighting from a 250W bulb only produced about 60% of the PAR as the sun:
http://www.advancedaquarist.com/2009/7/aafeature2
Ron Shimek did a study that showed how some corals do best at trapping foods at a water velocity of 15cm/sec. How many of us measure actual water velocity?
There are many factors that we do not measure that could be resulting in the demise of our corals.
Mitch