A pond fogger uses an ultrasonic transducer to create a cool, dense mist. The foggers used in ponds are typically shaped as floating plastic rings that hold a transducer plate three to four inches under the water’s surface. When power is applied, the transducer plate vibrates at an ultrasonic speed. This vibration causes the water in contact with the plate to break into extremely small droplets that are very similar to a natural fog. The vibrating plate also creates a pressure wave that pushes the droplets away, launching them into the air over the pond. Because they are so tiny, the vaporized droplets hang suspended in the air until the water vapor dissipates.
The ultrasonic vibrations created by pond foggers are not harmful to fish. Fish are neither attracted to them nor repelled by them. Because the water vapor is produced ultrasonically, the fog is cool to the touch. This same technology is used in greenhouses and terrariums to simulate humid rainforest environments.
A pond fogger is typically housed in a floating plastic ring that ensures contact with water for the transducer plate. This is important, because foggers cannot be run dry. Most pond foggers feature small, multicolored LED lighting effects. The glow of the lighting is amplified by the water droplets in the fog, and the effect is quite remarkable. Some foggers use different colored LEDs that slowly cycle through a series of calming hues.
The fog created by these devices is very fine, but they droplets are water vapor, and they are heavier than the surrounding air. The fog is suspended, but it remains low in the air. This feature allows foggers to be placed in fountains to create a fog that appears to spill over the fountain’s basin and flow into the pond’s surface. Foggers produce a similar effect when used in conjunction with a waterfall.
Foggers can also be used around pond plants that require especially high humidity levels, because the moisture clings to plant leaves as the fog passes over them. Ferns landscaped around the edges of a pond do well when foggers are used, and the humid environment is also attractive to native frogs and salamanders at the pond’s edging.