The present invention discloses an ultrasonic cleaner in which an automated ultrasonic cleaning operation is executed using an aqueous solution. The cleaner includes a tank having a valve means in fluid communication therewith, a bottom tank portion with at least one drainage aperture therethrough and at least one tank wall depending therefrom to provide a solution retention region. At least one ultrasonic transducer is removably secured to one of the tank bottom and tank wall. A partition in the solution retention region has at least one aperture defined therethrough and defines a service section and a support section thereby. A trigger means operatively disposed in the support section comprises a drainage flapper in operable communication with a signal means between a first rest position, in which the flapper impedes flow of the solution through the drainage aperture, and a second elevated position, in which the flapper is elevated relative to the drainage aperture to facilitate unimpeded fluid flow therethrough.