150w D.E MH Lamps

[James0_85]

how hight above the water should i put 150w D.E MH Lamps?

[PaulErik]

You should place them close to the water and bring the light up higher if the water heats up too much. I personally have mine about 5 inches from the water.

Hope that helps

[Nanook]

I have a couple of 250w DE metal halide pendants. I ran them over my 58g tank for a while, then my 120g tank. In my experience, the lightspread at less than 8-10" from the water really decreased the coverage. These bulbs also run very hot! On a 15g tank, if that is the one you are using them for, coverage shouldn't be too big of an issue with keeping them closer to the water's surface...just watch for overheating!


Nanook

[David Grigor]

Depends on a few things. Usually trial and error until you find the right combo.

In general the closest you can get to the water without causing excessive heat and still get good light spread is ideal. This distance varies based on pendant/reflector brand. So really there is no perfect answer.

[Fliger]

Yeah, it's basically trial & error. Last night I moved mine to 5" above the water line. Mine is an open top system so heating isn't really a problem. I think the biggest consideration is heat, and how much light spread you need. My tank is only 36" long, & I will place all my light loving dudes in an 18" column underneath the light since I don't get too much spread. I also suppliment with quite a bit of PC.

[James0_85]

the tank im going to use them for is 72" x 13" x 16" so ill put 3 of them 5" above the tank and see what happens , got them for a great price aswell $50 for 3 150 what lamps + globes :rollface:

[Fliger]

In my limited experience, I'd say take them a little higher then. If your tank is only 16" high, if you have any kind of a sandbed, you'll probably want to maximize spread. One for every two feet is usually mentioned with an 8+ inch hieght. Just mess around with them. My tank is over 20" high and I have mine about 6" now. It really limits the spread. I guess a big factor is the reflector that you have.

[Scleractinian]

It really depends on what you're trying to get light to (livestock) and on the fpucs/distribution of the reflector... check Sanjay's recent article in Advanced Aquarist (http://www.advancedaquarist.com/issues/mar2003/feature.htm) for info on the distribution of various reflectors. This article only presents part of his data (though he did present the rest at the Midwest Marine Confc.), look for more soon.

With a PFO mini-pendant, for example, you'd have to raise it relatively high to get decent coverage, but if you wanted to spotlight a particular colony, you could place the pendant much closer to the surface.