[Mike] lives in a temperate rainforest in Alaska (we figured from his website’s name) and uses a 570 gallon oil tank to supply ... and finally opted for an ultrasonic sensor.

The EPA recommends using distilled water to fill an ultrasonic humidifier’s tank. Distilled water still ... Without regular cleaning, the humidifier’s insides can become a breeding ground ...

But assuming all the nooks and crannies of a board can be dried out before power is applied, the cleaning solution itself should be of little concern. The main beef with ultrasonic cleaning seems ...