i actually got one thats too strong and let it run too long. they aren't necessarily a bad thing, but overusing one is definitely a bad thing. by the time i figured out what it was they were burnt pretty badly, like having a strong led too close kind of burns. all the plants effected by it made full recoveries, except the auto, which was stunted by it because it happened right at the very beginning of flower and stopped all the stretching the plant would have done.