[SerotoninJunkie]

I'm curious why no one has commented on the red stems and burnt leaf tips, red stems while your vegging can be a sign of either an N, P, or K deficiency as well as sulfer or magnesium. For anyone else with this kind of problem I'd vote definitely on a LOT more light, try mixing 1/4 or 1/2 tablespoon of epsom salts per gallon of water for magnesium and sulfer (most people say a full tablespoon but that will turn even a 7.5 ph level to drop below 6) as well as either more nutes with N,P and K or less fertilizer because there is nute lockout in the soil, which would account for the burnt tips. If you have bad water (like it's full of calcium) it can also result with a greater likelihood of lockout in the soil, sometimes a flush helps. This is all also assuming the PH is balanced between 6.2-7. Other tell tale signs of various possible deficiencies and issues, like the yellow leaves.

Anytime you aren't open to input from others you tend to do wrong things without knowing, just because all of your other plants grow fine in the same conditions doesn't mean that that MJ plant isn't just more sensitive to something then your others. Even variations in soil consistency can make a plant more prone to stunted growth.
ELDER GROWERS, tell me if I'm wrong or naive! I'm here to learn and help others, tell me if you think I'm wrong.