Halide height on shallow sps tank

[Proteus]

I'm looking for advise from halide experts on height on shallow tank

My tank is 12" deep painted black on two sides with black substrate. Acros range from 6" to 10" water depth. With a 250w 21k geissmann halide housed in a lumenarc mini stealth pendant. The light is around 10" from water surface. Photo period is 6 hours

Most acros are showing good color but some are still lacking.

Wondering how low I could set the light or if I should increase photo period.

I started at 14" above water surface lowering 2" every couple weeks

[Aquattro]

I usualy ran my 400s about 6 inches off the water, regardless of tank size. Currently running a bit higher, but I'm running 2 over a 40" tank. I think you could go 8 and increase photoperiod by an hour

[Proteus]

Thanks brad I will increase period today and watch. My only concern with height was that the reflector has better reflection than hammered units and combo fixtures

[Aquattro]

I use lumenarc reflectors, and the fish need sunglasses, but the corals love it. Remember, they come from under the sun :)

[Proteus]

Yep just didn't want to over do it I've had enough complications. Lol.

[Ryanerickson]

Didn't realize how low you can put these lights I measured my 2 400's today the bottom of the reflector was at 20" mark. I thought they should be high because of the tank only being 12" deep, guess I'm gonna slowing bring them down 5" today I know that's not slow but it's what it worked out to after building a new support system.