If i was you i would put those babies in to flower, they are going to triple in size, the pics on here are old i started flowering mine abd they blew up
I find that the lower leaves will sometimes turn yellow from when they touch the soil when the leaves droop, Cut those suckers off! think of a dieing plant you trim those dead leaves, its wasted energy.
Looks like the plants are going good.
1. The light needs to be switched the 2700k (warm white, Soft white). The cool whites (6500k) can still be used in flower but use 1 for every 5 like i did and you should get good results. The 2700k give off a more red light like what you see the sun do...