2x400w MH how high

[posjr]

I'm buying some Mh tonight 400w's x2 and dont know how high to put them. i'm puting them on a hang fixture i made. for a 100 gallon tank. with the mh there will be 1 40w and 2x65 compacts for now! they all will be artinics

[Rod Buehler]

I like to run my 400s about 6" above th ewater surface

[Typhon]

I recommend 9" from the water surface because of splashing and heat issues.

[posjr]

So i have no splashing but they do get hot really hot. so i'll go with 7 to 8 inch up. thanx

[pncstod]

Mine are 7 inches to the bottom of the bulb from the water's surface. I have 2 fans in the canopy and run no chiller. I do have a room a/c in the room for the hot days. No problems so far here:D