nikonosis
New member
I think you're probably alright at about 5", considering your tank's depth is 24", but hopefully someone else in a similar circumstance will chime in. My tank is 18" depth and I'm not using the optics, but I plan on adding optics (I'll leave them off the 30watt LED's) and raising my fixture up a little higher. I'll be borrowing a meter from someone in my reef club to figure out the PAR #'s. I would definitely try and see if you can borrow a meter, because the optics might be boosting PAR #'s too high for your tank.
Since I have optics on all bulbs I raised it up to about 12 inches above the water level. Gonna see how that works since no one has answered.