AquaPod 150W HQI Lamp Doesn't Always Start

[L33T]

In the past few days I've now had two instances where the aquarium light (Current AquaPod 150W HQI) didn't start. The fan started up, and I heard the humming and all, but the lamp didn't turn on (fully). Instead, I could see this purple-colored effect in the center of the bulb. After a few seconds, the effect would go away and the bulb would become entirely clear and unlit.

Then, if I wait enough time, I could turn back on the lamp and it would work successfully.

Is this a problem with the lamp, or the ballast?

Thanks!

 

[jojo1n2]

I would start with the lamp and see what happens. If the new acts the same, then It could be the ballast.