[NATIVEVAMAN]

I would say technically you dont have to much light,however,you have one 400 watt bulb over the center of a tank that should have two bulbs over it.So all or most of your light is concentrated in a small area.You could have as much as 13 watts per gallon in the center of your tank.Metal halide bulbs are designed to cover a 2x2 area on the surface of the water.You need a new light fixture.