Lighting upgrade

[JMAN]

I am considering adding a 175W 10K metal Halide to my 29 gal LPS and softie tank. I was thinking of getting a PFO ballast with the 24 inch reflector/socket that would allow me to attach the 2 75 watt VHO I have currently. What is the minimum height above the water (open top tank, plan to also install one of those cheap plastic fans in hood) to avoid temps over 80 degrees?

Also, would one actinic URI and one 50/50 URI in conjunction with the 10K MH be too blue? I like some blue opposed to the white light look.

 

[mariner]

As long as the room that the tank is in is temp controlled, the distance really won't matter. I've got a 90 with dual 250's about 5 inches off of the water with two clip on fans blowing on them and my temp has never gone over 80.