Week 5 Flower and Disaster.. HELP!?!

Up to this week all has been GREAT in the grow. I had to be gone for work for 2 days. I came back and one of my bulbs was blown (right side), and I noticed while changing it the spots on 3 of my plants (see picture). pH in the water tested fine, and PPM as well.

HELP!? Should i flush? is it nute burn? Does the light going out have anything to do with it?

looks like nute burn, you could flush it, and feed it nothing but Ph'd water for the next week, but the damage is done, just look towards new growth now.

thats not 'nute burn' with is a useless term for nutrient toxicity , that looks far more like downey mildew, check with some1 else but im really sure its leaf fungus.

Any idea on how to help it? Do we need more ventilation? We are using a bcnl producer. Any other ideas?