Metal halides

How high above the water should I have my lights?

 

It depends on the intensity of the lights you wish to use and how much space you wish to have to do aquarium maintainance.

 

I have a 125. Got it used. Got a pretty good deal but havent talked to the guy since I bought it and he had it broken down when I got it. I'm not sure of the halide wattage, but theres is 2 of them and they each have 1 96w by 10,000k lights and a 96w 420 actinic. I have had them right on top of the tank rim since I've had it going, but I just started wondering about this. The next place I could put it is about 14 inches above the tank and I dont know if that would be sufficent lighting.

 

mine are at ~ 10" and do fine. No spike in temp.

 

my 150s are ~10" too. Im not sure if my temperature during the day goes up due to ambient room temp or my lights. i think its the lights.

 

Take a look at the bulbs, it should say what wattage they are. You can also look at the ballast to see what it is rated for. You will need that info when you replace the bulbs anyhow, so it's good to know. For a 125G tank, I would imagine it would be dual 250W bulbs. I would keep them about a foot above the water to keep it from heating the tank too much.