Ballast choices
 

I have been given the chance to purchase a cheap 400 MH ballast & socket. I am told that the ballast will fire a M-59 or H-33 bulb. Is this compatable with standard aquarium bulbs? What is a 400w bulb in tech terms, M-??

Rick, that ballast will be fine. A normal 400w ballast is a M59.

The M designation is for the wattage and bulb type. A M59 is for 400 watt Metal Halide H33 is for 400 watt Mercury vapour.

You really need to know the bulb you are wanting to match. Unless you are using double ended bulbs or HQI bulbs the M59 balalst will drive almost all the Metal Halide aquarium bulbs.