leaves yellowing

Hello people I am just looking for some inputs, I am 7 weeks into flower and all the top leaves on my plants are turning yellow, I read it could be light burn but the closest plant is 18" away. I am using a 600w hps in a 4x4x7 tent with a 4" extraction and now I have a 4"intake fan what I set up...

Hello trusted folks from rollitup! Long time lurker, first time poster here... I'm actually going through my first growing experience and I gotta say it's damn satisfying seeing the lady grow. My project is not the most professional thing you'll ever see, that's for sure, but I'm a dedicated...