A surgical system controls a fluid and includes an irrigation line and a first fluid vessel for holding the irrigation fluid. The irrigation line connects the first fluid vessel to a handpiece. An aspiration input line connects a suction pump to the surgical handpiece and permits the suction pump to draw fluid through the surgical handpiece. A pressure sensor detects the pressure of the fluid in the aspiration input line. An aspiration output line connects the suction pump to a collection vessel to permit fluid from the suction pump to be conducted into the collection vessel. A second fluid vessel accommodates irrigation fluid therein and an aspiration ventilation line connects the second fluid vessel to the aspiration input line. A venting valve in the aspiration ventilation line is switchable in dependence upon the fluid pressure in the aspiration input line.