a safety device for use in a fluid transfer system for a swimming pool or similiar application , having a pump which draws water from a reservoir through one or more intake lines each extending from an open end at the reservoir to the pump intake . the device analyzes negative pressure levels in the system and , upon detecting a negative pressure level being outside of a selected operational range , the device deactivates the pump and triggers a vacuum breaker device to eliminate negative pressure in the system , by introducing air from atmosphere into the intake lines thereby removing suction at the open ends of the intake lines . the safety device may further activate warning devices including audible and visible alarms to indicate that the system has been deactivated .