I have 3 MH with the normal reflectors. How tall should my canopy be? I was in between three different heights...

Because the tank is viewable by both sides, I need to completely enclose the canopy (will be accessible from both sides). I will have fans at the top of the canopy to help ventilate, but that is about it....

  • 12" (but then my lights would pretty much be on top of my water and cooking the tank....no chiller)
  • 15" (a little relief)
  • 18" (allows me to get in and work on whatever I need to without fear of burning my arms or head on the lights......too often )

Any recommendations?