ok so maybe its too much nitrogen problem from reading this:
Nitrogen toxicity - too much nitrogen - Cannabis growing problem
Problem: Dark green leaves, weak stems, and overall slow growth. Marijuana leaves that are nitrogen toxic often get "The Claw" or talon-like leaves that are bent at the ends. The also do a weird curving / cupping that is often mistaken for overwatering, but is unique to nitrogen toxicity. You can this leaf "clawing" pictured to the right and below (click each picture for a close-up).
Leaves that turn into claws often start turning yellow and dying if the nitrogen toxicity is not treated, much like a nitrogen deficiency, only the leaves will continue to get more and more clawed. Leaves eventually turn yellow or brown and fall off. You can tell if yellowing is caused by too much nitrogen because the rest of the plant will be dark green, and the yellowing leaves will turn into claws first.
Different strains react differently to nitrogen toxicity. Some plants get dark green leaves with no clawing. Some strains will get leaves that do the weird 90 degree bend at the tips, while other strains or individual plants start curling like claws and then turn yellow / brown and fall off like a deficiency. Yet these are all signs of too much nitrogen.
Signs of Nitrogen Toxicity
Dark green leaves and foliage
Leaf tips may turn down, without signs of overwatering.
You may notice yellowing on the affected leaves or other signs of nutrient deficiencies as time goes on
Nitrogen toxicity is often but not always accompanied by nutrient burn
The Claw often seems random, affecting leaves here and there
Heat and pH problems will make the clawing worse, as they stress out the plant and lower her defenses
As time goes on, the claw leaves will eventually start turning yellow, getting spots, and dying.