how long did you let it run? It has to warm up the blue in the arc tube haves to heat up the gasses before it will ignite. It should only take a minute. If that don't work check the socket make sure the contact tab is not smashed down to much if you do that its a real good idea to unplug it before you mess with it. When I buy a new bulb from the grow store they score the bottom of the bulb that could be it to? Did you make sure its switched to mh and not hps?
Rubberbubbler Reviewed by Rubberbubbler on . 250 watt mh bulb not starting up i just bought a brand new Hydrofarm Sunburst (connected ballast) and a new mh bulb from lowes this weekend. it is a 250 watt sylvania bulb standard mh. When i went to turn it on for the first time it made a little noise but would not start up. i looked at the bulb and all i seen was a little blue reacting light in the bulb. Does anyone know if this is a bulb issue or a reflector/ballast issue. or am i just doing something wrong. any help would be much appreciated. Rating: 5