Lighting placement

[ZOAREEFTANK]

I've recently bought a used 120w taotronics led light for my 20 long that Is gonna be a reef tank. I'm jus having a problem finding the right placement for it. I've heard a few inches above the water
Line is good and I've also heard over a foot above is good. So I have no idea where to put it could anyone give me some suggestions? By the way it's not the dimmable version.

 

[thirty6]

I would placed it 12+" above surface. If it's not dimmable maybe slightly higher. Too much power from the light is not good, "burn" some corals

 

[ZOAREEFTANK]

Right now I have it probably over 2 feet cuz I was nervous about harming the corals in there