Well I just recently learned to much uv will do that although you didn't mention uv so I assume that's not the problem..from my personal knowledge is if you are using an LED light is it is producing too much light like a high ppfd it will also do that... yea that happened this grow so anyway I knew it was high but decided to leave it that way until it show a sign, it took 30 into flower to show the signs something wasn't quite right...so I turned it down 10% and things seem to be fine...now if all that mumbo jumbo I just blasted is any help to you I don't know...