How bright should 175W Metal Halide Be?

[markiezzi]

Hello,
I just purchased a used 175W metal halide light fixture. It is the hang from the ceiling bell shaped assembly with external ballast. I bought it used so not sure of the brand no labels. I let it run for an hour or so and it does not seem as bright as my 14W T5 lamps. I have a 20G Xtra high tank. How high should the light be mounted above the tank? Also are metal halides suppose to be ultra bright?
Thanks
any help would be great.
Mark

 

[reefforbrains]

what K is the bulb?
If its 6500k it is blinding bright, if 20,000k then it will almost look dim.
The usable output is different from bulb to bulb, and from maker to maker. What makes higher spec bulbs look dim is our human eyes can only see particular portions of the lighting spectrum. Coral and other photo critters use many spectrums.
6500k is bright but almost yellow
10,000k is more of a cleaner look.
12,000k is beginning in the blue side of the spectrum, wont apear as bright as a 6500k to your eye but the color will pick up better.
14000k has become the happy medium for most color with brightest eye apeal.
20,000k WILL apear dim to your eye but the colors will be intense. Almost photoshopped looking