Automatic purging of air from a fluid processing system

Systems and methods are provided for processing a fluid and then returning processed fluid and/or replacement fluid to a fluid recipient. The returning fluid is monitored to detect air therein and, if air is detected, steps are taken to automatically purge the air from the returning fluid without requiring the intervention of a system operator. The system may respond to detected air by pumping the processed fluid and/or replacement fluid away from the fluid recipient and into a processed fluid reservoir, where the air is purged from the processed fluid and/or replacement fluid. Thereafter, the weight of the processed fluid reservoir may be checked to confirm that sufficient fluid has been pumped back into the reservoir to remove the air. After it has been confirmed that the air has been purged from the fluid, the system may resume pumping the fluid toward the fluid recipient.