Index: firmware/App/Controllers/BalancingChamber.h
===================================================================
diff -u -r1d4d4b56b96a50cf32c9db93c322cc97a25cab7d -r1781335a8c1833fad17b275bf44c7f6675e68423
--- firmware/App/Controllers/BalancingChamber.h	(.../BalancingChamber.h)	(revision 1d4d4b56b96a50cf32c9db93c322cc97a25cab7d)
+++ firmware/App/Controllers/BalancingChamber.h	(.../BalancingChamber.h)	(revision 1781335a8c1833fad17b275bf44c7f6675e68423)
@@ -37,6 +37,7 @@
 #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.
+#define BAL_CHAMBER_FILL_VOLUME_ML                  30.0F              ///< Balancing chamber fill/drain volume per batch operation.
 
 /// balancing chamber data structure
 typedef struct