Help with new grow box?

[skunkface]

Hi. I just got 6 clones and a semi-vegged female plant from a friend. I built my first growbox. The dimensions are 2 1/2'w x 3 1/2'd x 4 1/2'.
I am currently running:
-400w mh bulb
-dayton 265cfm exhaust fan (w/ 4" duct leading out the top to a carbon scrubber)
-Home depot 4" duct fan on bottom side of box (w/ stocking over it stretched tight)
-4" computer fan (probably like 60-70 cfm) blowing air past reflector into exhaust duct
-tall oscillating skinny tower fan in corner set on "low"

I also have a clone box on top of the main box. There is a small fluorescent fixture and a heat pad to keep the clones nice and wet and humid. (They are almost rooted enough to transfer).

Everything has been going ok so far. The clones are showing roots and the main plant I got is doing ok. I recently lowered the light too far and it burned some of the leaves. I moved the light further away and added the tower fan and the computer fan. I have a digital thermometer/hygrometer inside the box. It is telling me that its around 80 degrees F. Is also telling me that it has ZERO humidity sometimes. Other times, when I open the box for 10 minutes or so, it will display around 30%. I have read that it should be around 50%. Is there a way to raise my humidity? I thought of using a humidifyer, but I've never heard of someone using a humidifier in a growroom. I always thought humidity was something that is usually high and needs to be corrected by lowering it. Do I have too much airflow? Anyway, thanks in advance. I appreciate any help I can get.

[SmknVTEC]

Yes,

You can use a humidifier in the grow room or just put an open bucket of water in the grow room. Humidity of 30% is fine but, lower than that I think is not good.