hi
Well, the air would be in a balloon type of bag, right? I don't see how the water would be able to push the air out. The water will be detected by a sensor, then the pump should start deflating. The pump-balloon air pressure system will be a closed sytem. Not gonna let water in.
I found this pump that ships cheaply: DC6-12V R385 Aquarium Fish Tank Round Water Air DC Diaphragm Pump Sale - Banggood USA-arrival notice-arrival notice
But I have no idea if I can reverse the airflow. I don't think so, it's an aquarium pump.
thx
babi