Abstract: A blood pump system and methods for the use and operation of such a blood system is described, wherein the blood pump system includes an implantable pump and an implantable flow measurement device. A processing device receives indications of a number of pump parameters such as pump voltage, pump current and pump speed. Flow rate is determined based on the pump parameters, and this determined flow rate is compared to the actual flow rate as measured by the flow measurement device. In certain embodiments, the flow measurement device may be periodically energized to make the comparison, then powered off to reduce power consumption. The time period in which the flow measurement device is powered off is based on the difference between the determined and the actual flow rates.