Index: firmware/App/Controllers/BalancingChamber.h
===================================================================
diff -u -r6bbe6e35f9c378ad8dd5be2edebb1cc1acd23d37 -r75ecd5ee8a56b8d9faef07cdeb0a8dc7975ff476
--- firmware/App/Controllers/BalancingChamber.h	(.../BalancingChamber.h)	(revision 6bbe6e35f9c378ad8dd5be2edebb1cc1acd23d37)
+++ firmware/App/Controllers/BalancingChamber.h	(.../BalancingChamber.h)	(revision 75ecd5ee8a56b8d9faef07cdeb0a8dc7975ff476)
@@ -35,7 +35,10 @@
 #define FRESH_DIAL_PRESSURE_MAX_PSIG                27.0F              ///< Maximum fresh dialysate pressure (D18) limit for balancing chamber fill operations.
 #define SPENT_DIAL_PRESSURE_MIN_PSIG                27.0F              ///< Minimum spent dialysate pressure (D51) limit for balancing chamber fill operations.
 #define SPENT_DIAL_PRESSURE_MAX_PSIG                31.0F              ///< Maximum spent dialysate pressure (D51) limit for balancing chamber fill operations.
+#define BC_FILL_PRESSURE_MIN_PSIG                   13.0F              ///< Minimum pressure (drop) during balancing chamber switching, indicates fill has been started / in progress.
+#define BC_FILL_PRESSURE_MAX_PSIG                   9.0F               ///< Maximum pressure (drop) during balancing chamber switching, indicates fill has been started / in progress.
 
+
 /// balancing chamber data structure
 typedef struct
 {