With reguards to the humidifier i run mine 24/7 through the veg stage and also run the circ fan and intake fans 24/7 through the entire grow
I wouldnt worry about rust the only problem running humidifier with tap water is that if you live in a hard water area you get lots of white mineral dust stuck to your fan blades and a few white spots on your leafs which u can blow off
humidifiers shut off when theres no water in them also dont worry dude youll be cool thats why we have fuses in our plugs
Hope this helps puts your mind at peace
