How far above the water do you keep your halides?

17" is pretty high. I believe most people have them down in the 6"-10" range to maximize the PAR output of the bulbs. If you are getting the desired color and growth, I would leave it. Otherwise you could experiment by lowering it slowly to see if you notice any difference.

 

I think a couple of inches a week would be ok. To be honest, I have never really bought into it and have always put my lights where I want them from the start. Seems how it's not my tank, I wouldn't recommend doing it. /site/DesktopModules/NTForums/themes/_default/emoticons/smile.gif

FWIW, I keep my lights 8" above the surface of the water.

 

I keep mine at about 10", but my opinion is that unless you are running a fog machine in the same room as your tank, then the height of the halides isn't going to make a tremendous difference. In fact, I think you could argue that mounting them higher should reduce the number distance the light has to travel through the water (where impurities might effect the light) due to the angles involved.
I do think adjusting the height is a good way to control temp swings though.
Again, this is my opinion and I'm sure it's not shared by the masses.
-JB

 

Mine are about 20" above the water.

I have the Lumenbrite reflectors which are so efficient that I can have them so high and still get great light.
Most generally people who see my tank and then see how high the lights are, cant believe I get away with them so high.
eins

 

I use 2 175w MH and there only 5" from water my temp changes about .5 degress. The down falls Ive seen from it so far is the angle of light is really small so it doesnt cover the entire tank like it should, and water evap is huge. Im currently working on a new canopy that is 8" from water with 3 250 MH. I didnt intend to use the short distance from water I just didnt have the time to build a new one and I didnt see a big problem from it. Just thought I throw my experience out there hope it helps.

 

I've got two 400's and they are 6 inches from the bottom of the bulb to the top of the water. And I run mine in a closed hood. Use fans in my sump and refugium to keep the heat under control. Took some tinkering but seems to work. I usually vary 1 degree in 24 hours.

 

Posted By einsteins on 01/31/2008 2:45 PM
Mine are about 20" above the water.
I have the Lumenbrite reflectors which are so efficient that I can have them so high and still get great light.
Most generally people who see my tank and then see how high the lights are, cant believe I get away with them so high.
eins
Eins, don't you have 2) 400W MH on a 120?

 

Yes I run 2x400w MH XM20k's
Tank is a 120

eins

 

have you guys that have your lights so far up above the norm ever used a light meter on your tank?.

just wondering.