A swimming pool cover pump works to remove water that has formed on top of your pool cover, either by rain or any other means. Depending on the size of your pool, and the type of cover you have, there are different sized pool cover pumps with automatic or manual operation. With the manual types, you have to monitor the progress of the pump and turn it off when the water has been evacuated. The automatic type of pool cover pump has sensors that monitor the water level on the cover and will automatically turn itself on, and run until all the water has been removed. At that point, the sensors cause the pump to shut itself off until the next time water is detected.