how high should halide be off the water?

[bongobrian]

Hey guys, I'm gonna start building a canopy for my 46 bow. I'm probably gonna end up with a 10,000k 175w metal halide or something comparable. I'm just wondering how tall should I build the canopy... in other words, how high off the water should the MH be? I was thinking 10-12" should be enough. What do guys recommend?

[kevinpo]

I'm running my 400W bulbs 8" off the tank top and 9" off the water surface. They are mounted in PFO reflectors.

HTH,
Kevin

[Chris Lakies]

I'm running my 175 Ushio 10K's about 4 inches off the water surface. I would not suggest this because there is a risk of water hitting the bulb and breaking it. Hopefully nothing happens from now until I set my 120 gallon up. I will be making my own hood and the lights will be about 10" off the water (2-400 watt 2-175 watt).

[ChrisIsBored]

Unless your tank has a lot of turbulent water at the surface, there's no reason you can't have your MH bulbs as low as 4" off the water. The only disadvantage would be added heat/evaporation.

I'm have my 250W's setup 7 inches off the waters surface.