Pic would help with a visual placement of coral & rock.
Being said, I have one on a nuvo 40, @ 9-10" above water and bleached a few frags with the color more than 20%.
(Although my rock work goes pretty high).
Every set up is different, you kinda got to find the balance, it takes a bit with these.
They are very powerful / intense lights, I don't know if it maybe too much for you, but
The thing is they are adjustable, dial down and see the reaction.
I wouldn't raise the light as the spill is pretty bad, but work with the color / intensities.
I run mine currently @
20% color (still ramping up)
85% intensity
LPS. 24" deep
Just to give idea.