I'm getting ready to build the canopy for my 20h. I'm going to install my 4x24 t5 lighting setup into it.

How far off of the water should I have these lights?

Also, should I have 3 or 4 inches above the lights to install fans, or would fans just below the lights do fine?

I had thought that if i put fans above the lights, blowing out it would help some of the rising heat leave the canopy.

Thx,
JD