In almost all cleaning applications, it is important to control the cavitation energy. When an insufficient amount of cavitation energy is provided, undesirably long process times may be required to obtain a desired level of cleaning, or in some cases, a desired level of surface cleaning may not be achievable. On the other hand, excessive cavitation energy near a substrate having delicate surfaces or components can cause substrate damage. The levels of cavitation energy are also critical in assuring complete and rapid cell disruption. The presence of solid impurities and dissolved gas determines the threshold of cavitation. Many use tap water, which varies widely in solid and gas content. A simple way of ensuring more uniform results is to use distilled water and then degass it. The liquid can now be engassed by bubbling the desired gas through it, which will ensure optimal cavitation.
From: Cavitation in Ultrasonic Cleaning and Cell Disruption