Two Ultrasonic Foggers 24VDC - Express Postage Included.
These foggers have a ceramic disc which vibrates at very high frequency.
The `sound waves’ break the liquid water into airborne fog particles.
Water, if not close to pH neutral, (and pH is a log scale – E.g. 8.0 is 100 times more alkali than 7.0) will throw a cast; calcium if the water is too alkali or rust if too acid.
The ceramic disc rim becomes fouled and the disc starts to vibrate off-frequency then stops.
We say on the label of our machines and in the book to monitor our water and treat it if it’s excessively off-basic.
Tank rain-water contains whatever dust settles on our roofs. Town water is treated only for contaminants not for its pH.
And of course, yes, you may have perfect water quality, used distilled water even, but a puck is an inexensive consumable item with an uncertain service life.
Try first whether soaking it in a CLR solution will clear the fouling.
We have replacement pucks as a two-buy.