A method for initiating cavitation within the fluid within a cavitation chamber is provided. In the cavitation preparatory steps, a hydraulically actuated piston is fully retracted and then the cavitation chamber is isolated. The hydraulic piston is then fully extended after which the chamber is partially opened until a predetermined cavitation piston position is obtained. After the chamber is once again isolated, cavities are formed and imploded by retracting and then extending the cavitation piston. At least one impeller, located within the cavitation chamber, is rotated in order to stabilize the cavities.