Hello I have a single scrog girl scout cookies, 2 and a half weeks into flowering that is having a problem that I cant identify the cause of. about a week into flowering i noticed the edges of its leaves starting to get a yellowish tint to them and tips started to curl down. as the problem progressed the leaves started to turn black and die off. I am thinking that it is a problem with my PH i am using botanicare nutrients, and the first thing i did was move the 150 watt hps up a couple inches and flushed the rockwool cube and all my PH seemed normal when I tested my solution. Any info or constructive criticism would be very appreciated.