DWC/LED and Humidity

I have a couple of new variables in this grow, but I noticed something with this particular configuration.
I find that once roots are dense, and hanging in a thick mass, my plants are extremely tolerant of low humidity.
My humidity is 5-15%, and I have seen no signs of wilt. Is there an impact on growth for a plant to absorb water through roots alone?
Right now I'm using 270W LED for my first time, and kept the light pretty close to the plants early on. I LST all tall sprouts with weighted carabiners. There was no stretch, and I have extremely low-riding plants that keep getting bushier. I will keep the light further away the next veg.
LED growing has really helped to simplify growing experience. None of the problems I had encountered with HID in the past. My 1000w HPS is such a beast, requires so much ventilation, power, and fire risk(to be honest with the combination of water and high amperage, a lot of grows I've seen are extremely hazardous).
I know I can't expect near the yield/quality, but LED seems like a good starter system for newbie(I promise to let you know how much less).

As long as your plants are not suffering it's good. Think of the Kush or dessert area where the finest hash plants grow. Not much humidity there. Makes for more trichomes to protect it's self from losing too much moister.
From what I have seen the LED's should do you quite well.

Is foliar feeding(6.0pH 50-100ppm grow nutes) something I should continue to do? I spray once a week. I see some white dried residue buildup on some the the larger fans though(Like Monica Lewenski's dress, zing!). Is that a concern?