Maybe rent a par meter and save money on a light. If corals are bleaching it's likely your lights are set too strong or some water parameters are off. You don't need lights to fix the bleaching unless you have a desire for new lights. I'm in the same boat as you but decided I'd rather spend that 600 on livestock and test kits.
Viparspectra? If you're not already doing these, these are things to keep in mind:
The BRS guys tested black boxes and without modification they need to be a pretty good distance from the water. Vipars need to be something like 20 inches up. You can hang them lower by removing some of the lenses to soften them up.
Did you slowly acclimate the corals to the light?
Almost everyone I've seen runs the whites at less than 20% and blues range from 50-80 most of the time.