Red Poison Auto & Black Cream Auto

The Black Cream on the left corner stretch a lot and on of the Red Poison is a little bit late and smaller than the other. She just start to flower. All the plants need very few fertilizer, i already have tip burn but nothing terrible. They flower a lot faster than i tought. Right now i'm trying to limit the stress of the plants and give them 25% of the recomended dosage every 3 watering. They are vigorous and react pretty well to "intense" LST.