ya, 400 watts seems like a lot for LPS, unless your tank is really deep, like 36 inches?
I can't keep any of my LPS above my sand bed otherwise they get roasted. In fact, some of them even have to sit under overhangs or they will get sunburned. I have 250 watts with a 20" water height. Lights are 8 or 10 inches from the water surface so 28" from the sandbed I guess.
What is it that you're not liking about the 250 watts on your tank?