How high are your 250W MHs off the water?

[Ceak]

I'm about to build my canopy and was wondering how high off the water my lights should be? I'm getting 250W Phoenix 14Ks and my tank is 30" deep. I plan to mix SPS, LPS, SPS and also have some clams...

thanks

[cwklinge]

I'm just building mine now and they are going to be around 10" off the water. I'm using PFO parallel reflectors that are 6" tall so I needed a little clearance on top to feed the fish.

[Ceak]

yeah...

initially I had planned to have my reflectors mounted on a wood pannel which I could slide forward and backwards and maybe have 2 or 3 sets of rails so I could have my lights at 3 different height levels...
I still think this is a good idea but now I'm concerned about heat, I read that alot of people have drilled holes directly above their reflectors to let air out and keep light in... In order to do this I would need my reflectors to be high up in the canopy at all times thus killing my multiple rail idea... :(

So I don't know what to do!

BTW my bulbs are DE

[aquaman2]

5 inchs

[impur]

11 inches for my pendant.

[Ti]

6"

[Bebo77]

6" interior 8" outer MH

[David Grigor]

depends on the reflector design what the minimum is. In general ranges between 6-8".

You don't want to go above the designed height if you can help it becuase every inch means less light reaches the tank.

Obviously if heat is an issue you may have to go higher but IMO that would be the only reason and I would exhaust all other options of cooling the tank down before resorting to raising the light.

[tekknoschtev]

While I dont have frags in the system to find out where "optimal is" I have a single 250W halide mounted perpendicular to the front of the tank in a diy spider-like reflector (piece of crap galvanized steel thing that is more of a light shield than a reflector) but because I plan on having some low light corals, it is on an adjustable setup so it can be anywhere from 3" to 28" for light acclimation purposes. Got a good deal on the setup - couldnt pass it up.

[kindafun]

8"

[Buster4900]

11"

[Sparkysreef]

9" from center of bulb to water surface

[Josh125]

10" from glass to water

[bigfalcon36]

8

[man1410]

14"

[jasonstr8up]

8"

[markdt]

There is a huge difference in hights. it looks like a range from 6 to 14 in. It looks like that it does not matter.

[VaderWS6]

12"