Metal Halides

[oak]

I was going to set up a 20g reef very soon and wanted to retrofit the Metal halide lighting. The tank demensions are 30" by 12" by 12". I am going to have two 70 watt fixtures or one 250 watt. Which would be better ? My concern about the 250 would be if it would cover the entire tank completly or if it would be noticably dimmer at each end. As far as the two 70s go it would just cost more. Thanks

 

[flricordia]

depends on the reflector but I would think a 250 would cover the tank jsut fine. I have a 250wt Pendant HQI over a 36" tand 10" above the water and it covers pretty much all of the tank.
2x70 wt would cover more but not much intensity depending on what you are awanting to kep. 12" deep tank is fairly shallow. 250wt might be too much in a canopy unless it is a tall one. 2x150wt would be better still. Jsut need to install fans, but I am sure you already know this.