low humidity questions

I am using 2x400 HPS growroom and i have a constant Humidity of 20% cant rise it, tried containers, steam humidifiers etc, none seem to work, any ideas?? also i am planning to use a protable AirConditioner for the summer, will it inevitably lower even more my humidity?

Plants seem to be doing great, any horrible consecuences of growing with 20% humidity

thanks

Sounds like you need a spray bottle. Mist once in a while if you cannot increase humidity.