An ultrasonic surgical instrument including a blade that treats tissue and a fluid control system to cool the blade by pumping cooling fluid through the blade. The blade defines a blade lumen in fluid contact with an inflow and return conduit of the fluid control system. The inflow conduit defines an open distal end positioned within the blade lumen adjacent the distal end of the blade lumen and the return conduit defines an open distal end positioned within the blade lumen adjacent the proximal end of the blade lumen. The fluid control system may further include a fluid reservoir holding the cooling fluid and an inflow pump. The inflow pump is configured to deliver the fluid from the fluid reservoir, through the inflow conduit and the blade lumen, and into return conduit.