How much lighting is too much?

[fishdude]

Happy New Year

My first question of the year.

I have a 120 gallon reef tank (and I'm green at this) that I have been running on a 20 000k metal halide and a strip 10000K just to add some yellow back.
I have no hard corals but a Maxima (blue? speceis) that require lots of light.
Is that enough light to grow hard corals? I have another 250 metal halide system now that I can hook up somewhere. So my question is.
Are two 250 watt mth bulbs too much or can I get by with what I have?
if I get the total 500 watts (I'll take out the strip) wil I have to but my bubble corals and mushrooms on the bottom?
your opinions please.

FD