A liquid condition sensor configured to monitor the condition of a liquid in an ultrasonic cleaning system tank, the liquid condition sensor including a first circuit configured to detect a signal transmitted from an ultrasonic generator to one or more ultrasonic transducers located in the tank. The liquid condition sensor further includes a second circuit coupled to the first circuit, the second circuit configured to determine if the signal is indicative of one of a suboptimal liquid level, and an unacceptably high concentration of dissolved gases in the cleaning liquid, and a third circuit coupled to the second circuit, the third circuit configured to provide a warning if one of a suboptimal liquid level, and an unacceptably high concentration of dissolved gases in the cleaning liquid is indicated by the second circuit.