I've been using the Nova Extreme t5 HO on my reef for a while now. It's suddenly developed a problem. It's a 4x, and two of the bulbs work and the other two don't. I replaced the bulbs, but that didn't help. What happens is that when the timer turns the one side on, the bulbs flash on and then shut off. It seems like they want to work, but for some reason can't. Do you think the ballast needs to be replaced or could it be something different?