Update:

After dropping the lights I had a good response at first, but throughout the week they started wilting again and some of the leaves have yellowed. I'm wondering if this could have happened when I ran out of ph down and used white vinegar instead.

I flushed today and used fresh nutes, also plucked out the weakest plant of the bunch. I have the lights about 2 inches above right now, hoping that perhaps the vinegar threw them off or something.

Any thoughts?