LED Height above water?

[hilltopreef]

I have a 120 watt (40 x 3 watt) 1:1 blue white led pendant. I Had light suspended at 8" above water surface and corals didn't like it. Burning according to LFS. The LFS said to raise them to 18". At what height do some of you advise? Tank is 60 gallon cube (24x24x24) with acros on top of reef (approx 6" depth) and lps lower and on bottom with 5 inch sand bed with plenum.

 

[DoubleM 10]

im not light expert but i would start the fixture higher. 18-20in sounds fine and the every week lower it 5in till you get the desired level. the corals will need to adjust to the light. maybe someone with moe experience will chime in here

 

[hilltopreef]

Thanks I look forward to all input. That is what I am planning to do probably a couple of week between each lowering to an acceptable level.

 

[hilltopreef]

Any one else have an opinion?

 

[nikon187]

What optics are on the led. This will determine how high to hang them. With tight 40 degree optics, 8-12 inches seems to be the norm depending on tank depth. 70 , 80, or 120 degree optics then the led can be placed alot closer as the light is much more spread out.

 

[The Grizz]

Are your LED's dimmable? Sounds like the intensity needs to be decreased. My DIY LED's are about 8" above the water & my tank is 18" deep.

 

[hilltopreef]

The light is not dimmable. Also the seller lists it as 60/90/120 mixed leds.