bulb life

Hello all, This is my first post after many informative learning sessions. This is my first grow, I'm running 600w mh/hps in a 31"x 31"x 71" tent. Been up and running beautifully for a week and when I went to check on my baby girls about 2 hours after lights on and....the lights WEREN'T on but...

Hello, I have am going through the HPS bulbs I have stored away and the majority of them have around this much use: Some have burn marks on the bulbs, is it dangerous to use them? Does this effect lumens? How much of the tube blackens before major effects to lumens? I tried searching for...