A controller for an implantable blood pump, the implantable blood pump having an impeller. The controller includes processing circuitry configured to reduce a speed of the impeller from a set speed to a first reduced speed if a first predetermined amount of time of detected suction events occurs during a first time interval and increase the speed of the impeller from the first reduced speed if a second predetermined amount of time or less of detected suction events occur during a second time interval and a third predetermined amount of time or less of detected suction events.