New lighting problem, my coral turning brown

[clownfool]

I had a 46g bowfront reef with a 150w HQI light. I bought a new light that is 250w HQI. Before the new light my tank looked really dark so I upgraded my light to 250w. The tank is greatly brighter now. My pokerstar monti polyps changed from green to brown since I changed my light. The bulb in the 150w light was a XM 15K and was very blue, now I have a oddesy 250w 15K bulb and is very bright white. Could the new light being so bright make my pokerstar monti turn brown? If I should use a different bulb what would you recommend? I like the look of the 250w bulb. The monti was about 5in from the top, and the light is about 3in from the water level using the legs that came with it. My water parameters are

Chiller temp is 78
Cal 420
Alk 2.5
Salinity 1.023
ammonia 0
nitrite 0
nitrate 0-5




please help me out

 

[Brian5000]

The blue in your light is what gives your corals color (UV absorbing pigment). If your light is less blue, then they don't need as much pigment and the defult color is zooanthella brown.

I'm guessing you either got a different K light than you thought, or the brand is just a lot whiter than your previous light.
_________________
Honda CB250RS

 

[cindre2000]

It is normal for coral to brown out under new lighting, it can take a while for the corals to color back up.

 

[Anonymous]

I'd test for phospates, too.