Lighting questions

Yeah that's a toughie. 8 or 9 inches is generally recommended, but I tend to go a few inches higher. That said, I tend to doubt the difference in heat between the two would merit going with the 175s. That's just a hunch. Can you modify the canopy to vent better?

 

My canopy is open in the back with fans on either side blowing in one direction along the lenght of the canopy.  My 175 watt lamps are about 10 inches from the water line.  No real hat problems even without the fans on normal days.

 

I dont think I could modify the canopy but my canopy is also open back and the fans are toward the front of the canopy in the top both facing up "since heat rises" so it will be pulling air from the back of the canopy over the lights and out the top. my only problem with this set up is I dont want to put the lives of $100's of dollars of marine life in the hands of 2 fans. I would be upset if I came home from work one day and my fans failed and all my fish were dead, but I guess I have to if I want decent lighting.