Metal Halide height

[nvmycj]

Hi guys!
I'm having my buddy that built my stand, build me a canopy for my BioCube 29gallon. I'm having a canopy built to hide my lighting because I don't want to be blinded by the lights while watching TV in my living room.
My question,....how high off the water does the MH have to be? I've seen the HQI bulbs be about 8 inches off the water. Any suggestions?
Thanks!

 

[nikesb]

8-12 is good for a 150w

 

[joneyelik1996]

I worked on a 36 plant bloom with four plants under each light, so 9 HPS fixtures at 1,000 watts each. Replaced the four corner lights with CMH 915 watts. Had to raise them to 31/2 feet above the canopy so as not to give the Nox Vidmate VLC plants too much light.