I bought a Metrolight electronic HID ballast to run a 150w Metal Halide lamp for my reef tank, and the ballast has the ability to dim the lamp from 100%-50% output. It uses a 0-10v dimmer switch to control the ballast, which seems to be the same kind of switch people install in their homes to dim room lighting. My problem at the moment is that all the dimmer switches I've been able to find are the ones that need to be installed into the wall plates. I would like to find a solution that I can mount onto or next to my tank's stand. Aren't the dimmers basically potentiometers(either slide or rotary)? I'm gonna add the wiring diagram for the ballast, but it looks like the ballast feeds a 10v signal into the dimmer/pot, and the voltage that is returned correlates to the output of the ballast(I.e. 10v = 100%, 0v = 50%). Is that correct? If so then I just need a pot, but how do I know what resistance value is needed for my ballast?

 

The mains wall dimmers are no good for this control, you need a 0 to 10V dc supply, if you short the grey and purple wires together it will dim to 50% instantly.

 

I actually just tried that and got no change in the lamps brightness.
On closer inspection, the ballast I have is not the exact same model number(but same base). The ballast I have has a a different setup, so I'm gonna contact the Manufacturer for help.
Thanks