I am a very keen to learn noob 4 weeks into my first grow. I decided to go with barneys vanilla kush seeds and use a 600w light in my 1x1 tent plant setup. They started off perfectly and I was really proud of them but over the last couple of weeks 2 out of my 4 plants have gone from perfect green...to light green....to slightly yellow.. And now yellow fan leaves with brown spots appearing. I use canna coco and have purchased many nutrients... For veg stage i have canna coco A&B, but have recently purchased canna rhizotonic as I was told it might help them a bit?? The new growth is coming through but although it starts green it turns yellow after a couple of days and as a first time grower this is literally like watching a child screaming out for help but not being able to know what it needs. I have tried flushing... Under feeding, Adjusting the light height and creating more air flow but no luck I'm getting that comforting green look back into my kush plants please someone help me? I will be more than happy to upload pics if someone is patient enough to kindly guide me through this website. p.s I was considering including some bat guano in my next feed as it could be a nitrogen deficiency that is being stubborn.... Thanks for your help everyone. Joe