Im thinking of building a canopy for a 24x24x12 shallow reef housing a MH fixture and maybe some hydras. How far away should i keep the MH from the hydras so it doesnt do heat damage, should i add fans or head shielding? what if i vented the top of the canopy or left the top totally open? also should I have a standoff from the MH fixture and the wood? any chance of it catching fire?

