Are you asking if water hurts plants?

I used an ultrasonic cool mist humidifier when I started out. What I noticed about 3 weeks in was that the mist was leaving a white powdery mineral deposit on everything. Leaves, fans and walls. It clogged my filter too. I took the pre filter outside and shook a ton of it out, so much that the grass turned white. I got rid of the humidifier and those problems. Also if it’s running all the time blowing wet air on the leaves I would think that would open the door for powdery mildew.

Use filtered water in your humidifier. That will keep the powdery stuff. That’s most likely calcium buildup. Get a humidifier with an auto shut off at the humidity you want. The humidity sensor in them isn’t very accurate so maybe set it a lower humidity than you want.

Only RO or distilled water for humidifiers….

https://vivosun.com/vivosun-aerostream-h19-humidifier-p152726596818619753-v152726596818619752

This is what I run. It’s freaking sweet.