Index: firmware/App/Controllers/BalancingChamber.c
===================================================================
diff -u -ra631e128cd6be44aa232e23b58a229bfb8fe9043 -r43ebe58702128e865210533f9e6deaf13f99d262
--- firmware/App/Controllers/BalancingChamber.c	(.../BalancingChamber.c)	(revision a631e128cd6be44aa232e23b58a229bfb8fe9043)
+++ firmware/App/Controllers/BalancingChamber.c	(.../BalancingChamber.c)	(revision 43ebe58702128e865210533f9e6deaf13f99d262)
@@ -96,6 +96,7 @@
 static U32 balChamberFillTimeoutCount;                                                          ///< Timeout count (in task interval) to detect BC fill timeout.
 static S32 diffSpentFillCompleteCount;                                                          ///< Difference between spent target fill to actual fill count
 static BOOL isSpentFillComplete;                                                                ///< Flag indicating spent side fill complete.
+static BOOL isFreshSideValvesClosed;                                                            ///< Flag indicating fresh-side BC valves are closed while spent side may still be filling.
 static F32 lastPrevSpentDialPressure;                                                           ///< Low-Qd slope: spent pressure last sample of dosing (tick before VALVES_CLOSE); then n-2 in VC.
 static F32 prevSpentDialPressure;                                                               ///< Spent pressure previous sample (n-1) during VALVES_CLOSE for low-Qd slope detection.
 static U32 spentFillRiseHitCount;                                                               ///< Low-Qd slope: counted rise hits (only incremented when in timing window).
@@ -127,6 +128,9 @@
 static void applyBalChamberSwitchingPeriod( F32 tdDialysateFlowrate );
 static BOOL isBalChamberTimeBasedSwitching( void );
 static void scheduleFirstCycleRelaxAfterQdApply( void );
+static void valveControlForBCState1FreshSideClose( void );
+static void valveControlForBCState2FreshSideClose( void );
+static void closeFreshSideValvesWhenFillComplete( void );
 
 /*********************************************************************//**
  * @brief
@@ -179,6 +183,7 @@
     spentFillRiseHitCount                       = 0;
     spentFillRiseMissCounter                    = 0;
     isSpentFillComplete                         = FALSE;
+    isFreshSideValvesClosed                     = FALSE;
     isBalChamberSwitchingActive                 = FALSE;
     isBalChamberSwitchingOnRequested            = FALSE;
     isBalChamberSwitchingOffRequested           = FALSE;
@@ -311,6 +316,7 @@
         spentFillRiseHitCount             = 0;
         spentFillRiseMissCounter          = 0;
         isSpentFillComplete               = FALSE;
+        isFreshSideValvesClosed           = FALSE;
         spentDialPressure                 = getFilteredPressure( D51_PRES );
         lastPrevSpentDialPressure         = spentDialPressure;
         prevSpentDialPressure             = spentDialPressure;
@@ -620,6 +626,59 @@
 
 /*********************************************************************//**
  * @brief
+ * The valveControlForBCState1FreshSideClose function closes only the fresh-side
+ * balancing chamber valves opened during state 1 fill.
+ * @details \b Inputs: none
+ * @details \b Outputs: valve states
+ * @return none.
+ *************************************************************************/
+static void valveControlForBCState1FreshSideClose( void )
+{
+    setValveState( D19_VALV, VALVE_STATE_CLOSED );
+    setValveState( D22_VALV, VALVE_STATE_CLOSED );
+}
+
+/*********************************************************************//**
+ * @brief
+ * The valveControlForBCState2FreshSideClose function closes only the fresh-side
+ * balancing chamber valves opened during state 2 fill.
+ * @details \b Inputs: none
+ * @details \b Outputs: valve states
+ * @return none.
+ *************************************************************************/
+static void valveControlForBCState2FreshSideClose( void )
+{
+    setValveState( D20_VALV, VALVE_STATE_CLOSED );
+    setValveState( D21_VALV, VALVE_STATE_CLOSED );
+}
+
+/*********************************************************************//**
+ * @brief
+ * The closeFreshSideValvesWhenFillComplete function closes the fresh-side BC
+ * valves once fresh fill is detected, without waiting for spent fill.
+ * @details \b Inputs: balChamberSWState, isPressureStabilizedDuringFill, isFreshSideValvesClosed
+ * @details \b Outputs: isFreshSideValvesClosed, valve states
+ * @return none.
+ *************************************************************************/
+static void closeFreshSideValvesWhenFillComplete( void )
+{
+    if ( ( TRUE == isPressureStabilizedDuringFill ) && ( FALSE == isFreshSideValvesClosed ) )
+    {
+        if ( BAL_CHAMBER_SW_STATE1 == balChamberSWState )
+        {
+            valveControlForBCState1FreshSideClose();
+        }
+        else
+        {
+            valveControlForBCState2FreshSideClose();
+        }
+
+        isFreshSideValvesClosed = TRUE;
+    }
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleBalChamberState1FillStart function handles the balancing chamber
  * state 1 fill and time to fill chamber counter being updated.
  * @details \b Inputs: Pressure
@@ -645,6 +704,7 @@
     spentFillRiseHitCount               = 0;
     spentFillRiseMissCounter            = 0;
     isSpentFillComplete                 = FALSE;
+    isFreshSideValvesClosed             = FALSE;
 
     if ( FALSE == getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) )
     {
@@ -775,7 +835,6 @@
 static BAL_CHAMBER_EXEC_STATE_T handleBalChamberState1FillDetectComplete( void )
 {
     BAL_CHAMBER_EXEC_STATE_T state  = BAL_CHAMBER_STATE1_FILL_DETECT_COMPLETE;
-    BOOL isBothFillsComplete        = FALSE;
     BOOL isFirstCycleNotDone        = FALSE;
     BOOL isFillCompleteOrFirstCycle = FALSE;
 
@@ -806,16 +865,17 @@
         }
     }
 
+    closeFreshSideValvesWhenFillComplete();
+
     checkSpentFillComplete( spentDialPressure );
 
-    // Check both spent and fresh side fill is complete
-    isBothFillsComplete = ( ( TRUE == isSpentFillComplete ) && ( TRUE == isPressureStabilizedDuringFill ) ) ? TRUE : FALSE;
     isFirstCycleNotDone = ( ( FALSE == isFirstCycleBCSwitchingCompleted ) &&
                             ( currentBalChamberSwitchingCounter >= balChamberValveClosePeriod ) ) ? TRUE : FALSE;
 
     if ( FALSE == getBalChamberSwitchingOnlyStatus() )
     {
-        isFillCompleteOrFirstCycle = ( ( TRUE == isBothFillsComplete ) || ( TRUE == isFirstCycleNotDone ) ) ? TRUE : FALSE;
+        isFillCompleteOrFirstCycle = ( ( ( TRUE == isSpentFillComplete ) && ( TRUE == isFreshSideValvesClosed ) ) ||
+                                       ( TRUE == isFirstCycleNotDone ) ) ? TRUE : FALSE;
     }
 
     if ( ( TRUE == isFillCompleteOrFirstCycle ) ||
@@ -963,6 +1023,7 @@
     spentFillRiseHitCount               = 0;
     spentFillRiseMissCounter            = 0;
     isSpentFillComplete                 = FALSE;
+    isFreshSideValvesClosed             = FALSE;
 
     if ( FALSE == getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) )
     {
@@ -1036,7 +1097,6 @@
 static BAL_CHAMBER_EXEC_STATE_T handleBalChamberState2FillDetectComplete( void )
 {
     BAL_CHAMBER_EXEC_STATE_T state  = BAL_CHAMBER_STATE2_FILL_DETECT_COMPLETE;
-    BOOL isBothFillsComplete        = FALSE;
     BOOL isFirstCycleNotDone        = FALSE;
     BOOL isFillCompleteOrFirstCycle = FALSE;
 
@@ -1067,26 +1127,17 @@
         state = BAL_CHAMBER_STATE_IDLE;
     }
 
-    // Check fresh dialysate pressure back in range to indicate fill complete.
-    if ( ( freshDialPressure >= FRESH_DIAL_PRESSURE_MIN_PSIG ) && ( freshDialPressure <= FRESH_DIAL_PRESSURE_MAX_PSIG ) )
-    {
-        if ( ++balChamberFillCompleteStablePressureCounter >= BAL_CHAMBER_FILL_COMPLETE_MS )
-        {
-            // stabilized pressure indicating fresh side fill is complete
-            isPressureStabilizedDuringFill = TRUE;
-        }
-    }
+    closeFreshSideValvesWhenFillComplete();
 
     checkSpentFillComplete( spentDialPressure );
 
-    // Check switching cycle time or pressure check for valve closure
-    isBothFillsComplete = ( ( TRUE == isSpentFillComplete ) && ( TRUE == isPressureStabilizedDuringFill ) ) ? TRUE : FALSE;
     isFirstCycleNotDone = ( ( FALSE == isFirstCycleBCSwitchingCompleted ) &&
                             ( currentBalChamberSwitchingCounter >= balChamberValveClosePeriod ) ) ? TRUE : FALSE;
 
     if ( FALSE == getBalChamberSwitchingOnlyStatus() )
     {
-        isFillCompleteOrFirstCycle = ( ( TRUE == isBothFillsComplete ) || ( TRUE == isFirstCycleNotDone ) ) ? TRUE : FALSE;
+        isFillCompleteOrFirstCycle = ( ( ( TRUE == isSpentFillComplete ) && ( TRUE == isFreshSideValvesClosed ) ) ||
+                                       ( TRUE == isFirstCycleNotDone ) ) ? TRUE : FALSE;
     }
 
     if ( ( TRUE == isFillCompleteOrFirstCycle ) ||
@@ -1459,6 +1510,66 @@
 
 /*********************************************************************//**
  * @brief
+ * The getBalChamberFreshSideValvesClosedStatus function returns whether the
+ * fresh-side balancing chamber valves are closed for the current switch state.
+ * @details \b Inputs: isFreshSideValvesClosed
+ * @details \b Outputs: none
+ * @return TRUE when fresh-side BC valves are closed.
+ *************************************************************************/
+BOOL getBalChamberFreshSideValvesClosedStatus( void )
+{
+    return isFreshSideValvesClosed;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The getBalChamberFreshFillCompleteStatus function returns whether fresh-side
+ * fill completed during the current BC switch cycle.
+ * @details \b Inputs: isPressureStabilizedDuringFill
+ * @details \b Outputs: none
+ * @return TRUE when fresh-side fill is complete.
+ *************************************************************************/
+BOOL getBalChamberFreshFillCompleteStatus( void )
+{
+    return isPressureStabilizedDuringFill;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The getBalChamberSpentFillCompleteStatus function returns whether spent-side
+ * fill completed during the current BC switch cycle.
+ * @details \b Inputs: isSpentFillComplete
+ * @details \b Outputs: none
+ * @return TRUE when spent-side fill is complete.
+ *************************************************************************/
+BOOL getBalChamberSpentFillCompleteStatus( void )
+{
+    return isSpentFillComplete;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The isBalChamberSwitchImminent function returns whether the balancing chamber
+ * is within the valve-close window (50 ms) before switching.
+ * @details \b Inputs: currentBalChamberSwitchingCounter, balChamberValveClosePeriod
+ * @details \b Outputs: none
+ * @return TRUE when BC switch is imminent.
+ *************************************************************************/
+BOOL isBalChamberSwitchImminent( void )
+{
+    BOOL result = FALSE;
+
+    if ( ( balChamberValveClosePeriod > 0 ) &&
+         ( currentBalChamberSwitchingCounter >= balChamberValveClosePeriod ) )
+    {
+        result = TRUE;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The getBalChamberSwitchingFreq function gets the balancing chamber switching
  * frequency value.
  * @details \b Inputs: balChamberSwitchingFreq