Looks like consistent overwatering and possibly time to up their nutes a tad, and/or give 'em a shot of unsulfered molasses at 1 tsp per gallon. Cannabis prefers a wet-dry cycle, so give ample time for drying the rootball a tad after a flush, and don't let the rootball sit in the runoff water. Try and get comfortable with the weight of your pots full, and their weight dry. Helps keep ya from overwatering.

I'm assuming you have the headroom for taller plants, since you're going with the big gun. (1000w) Yours looks like an indica dominate strain though and it's flowering time suggests the same, so it will be likely to have limited stretch.