Height above water / glass - 150W MH?

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Hi,

 

I'm thinking of getting a 150Watt Metal Halide, running 10 000K bulb. The ballast and ignitor are going to be seperate, behind my tank on the desk. The light and reflector, I would like to put in my existing hood. I have a sheet of cover glass over my tank to prevent evaporation.

 

So, that means that my light will be about 6 inch from the top of the water (about 4 inch above the glass sheet). Is this OK? It's on a 24gallon long tank.

 

Thanks

 

Evan

Cape Town.