Just Metal Halides
 

I was thinking that I might go with two 175Watt MH for my 38gallon tank that I want to get. Can you run a reef just off halides, if say I got one bulb in the 6500K and the other in the 12000K? Would 350watts be too much for a 38 gallon?

Thanks,Greg

How long is your tank? You may end up with a blue side and a yellow side unless you mount the bulbs right beside each other. Why the different temp bulbs?

It has the same dimensions as a 33 accept tha it is 2" taller, not sure what they are though,because i don't have the tank yet. I was going to go with the to different temp. bulbs, so that I would be able to get the full spectrum, and not have to use actinics. Wouldn't I have to?

Greg, I wouldn't mix the two colors personally, but that's just my opinion. If you just used 10k bulb(s), you don't NEED actinics...depends on what you like to look at.
With that tank, you could use a single bulb and have the lower light animals towards the edges. You could use a 400w Radium and not have actinics, but you might need to raise the bulb higher. I probably would only use a singel bulb anless you were going to pack the tank with SPS.