It is invisible to the human eye, but with the SonoCheck™ you can test for the presence of cavitation energy - the cleaning power - of your ultra-sonic cleaner. Ultrasonic cleaning is a result of sound waves introduced into a cleaning liquid by a series of transducers. The sound travels throughout the tank and creates waves of compression and expansion. During the expansion wave, molecules of the liquid are pulled dramatically, ripping them apart. This creates microscopic vacuum cavities. As the pressure around these cavities becomes greater, they collapse violently, forming voids - a process called cavitation. This creates extreme temperature and combines with the velocity of the liquid jet to deliver a very intense cleaning action in a minute area. When the ultrasonic cleaner is supplying sufficient energy and conditions are correct, SonoCheck™ will change color. Problems such as insufficient energy, overloading, water level, improper temperature and degassing will increase the time needed for the color change. In the case of major problems, the SonoCheck™ will not change color at all.