Help a newbie out please.

I am new to growing indoors, so there's gonna be some mistakes here and there. I have noticed that some leaves on the girls have been kinda curling downwards. Even the new growing leaves. They are in a 4x2 tent. Average temps are 70-75F and humidity is pretty low at 20% which I know that the average humidity should be around 40-50.
Btw, the girls are Do-Si-Dos

Nothing?

What lights are you using? Are they cuttings? Fertilisers? What soil mix?

Hey they always been curling or have they just started?