A dialysis system that includes a dialysis machine, a tube connected to the dialysis machine, and a sensor system. The sensor system includes a head having a slot configured to receive the tube and a plurality of sensors secured to the head adjacent the slot. At least one of the plurality of sensors includes a light emitting element configured to transmit light through the tube when the tube is disposed in the slot and a light receiving element configured to receive the light emitted by the light emitting element after the light passes trough the tube.
