Here's that trouble shooting form http://boards.cannabis.com/plant-pro...anted-one.html

I would say it's a nutrient deficiency It's a good thing you have that 20 20 20 cause that should clear it right up. Check out Revised: The Complete Guide To Sick Plants,pH and Pest Troubles - PlanetGanja.com for a more specific diagnosis on nutrient deficiency.
dragula05 Reviewed by dragula05 on . new leaf problem need ur help. I have a 3 1/2 weeks old plant. the seed came from a bag of dank buds I had once. that plant is on the left side of the pix. the other one is a clone from my outdoor garden. what I have been giving it is 5.9-6.2 phed water then when the soil drys out agen I then give it 5.9-6.2 water mixed with some maxicrop original liqufied seaweed. I got the seaweed stuff from a garden center. they said it would work well for grow veggies and stuff like that. anyway hears what the leafs look like. so Rating: 5