A pneumatically driven fluid pump apparatus is disclosed which includes a pump casing having an inner wall, a pump cap secured at a first end of the pump casing, and a liquid discharge tube in communication with the pump cap and extending at least partially within an interior area of the pump casing toward a second end of the pump casing, and where fluid is admitted into the pump casing at the second end. The pump cap has an airflow inlet for receiving a pressurized airflow from an external pressurized air source, which helps displace liquid collecting within the pump casing upwardly through the liquid discharge tube. A flow channeling subsystem is in communication with the airflow inlet and directs the pressurized airflow towards the inner wall of the pump casing to create a swirling airflow within the pump casing that extends along at least portions of the inner wall. The swirling airflow entrains fluid within the pump causing the fluid to move in a circumferential swirling fashion toward the second end of the pump casing, which helps to clean the inner wall of the pump casing.