Index: firmware/App/Modes/ModePreTreat.c
===================================================================
diff -u -r0994065cce7875df917e6f96e7a0b78109980752 -r9e03fdc8048e93c5bf32372a9f951b4456d16392
--- firmware/App/Modes/ModePreTreat.c	(.../ModePreTreat.c)	(revision 0994065cce7875df917e6f96e7a0b78109980752)
+++ firmware/App/Modes/ModePreTreat.c	(.../ModePreTreat.c)	(revision 9e03fdc8048e93c5bf32372a9f951b4456d16392)
@@ -44,6 +44,7 @@
 
 #define DIP_PATIENT_CONNECTION_FLOW_RATE_ML_MIN         100             ///< Patient connection sub-mode dialysate inlet pump flow rate in mL/min.
 
+#define PRE_TREATMENT_FLUSH_RESERVOIR_VOLUME_ML         500             ///< Fill reservoir to this volume (in mL) to flush filter and lines.
 #define PRE_TREATMENT_FILL_RESERVOIR_ONE_VOLUME_ML      1300            ///< Fill reservoir one to this volume (in mL) during pre-treatment mode.
 #define PRE_TREATMENT_FILL_RESERVOIR_TWO_VOLUME_ML      700             ///< Fill reservoir two to this volume (in mL) during pre-treatment mode.
 
@@ -81,6 +82,7 @@
 static PRE_TREATMENT_RESERVOIR_MGMT_STATE_T currentReservoirMgmtState;  ///< Current pre-treatment reservoir management state.
 static BOOL fillReservoirOneStartRequested;                             ///< Flag indicates fill reservoir one has been requested.
 static BOOL reservoirFilledStatus[ NUM_OF_DG_RESERVOIRS ];              ///< Flag indicates a reservoir has been filled.
+static BOOL reservoirFlushedStatus[ NUM_OF_DG_RESERVOIRS ];             ///< Flag indicates a reservoir has been flushed.
 
 // ********** private function prototypes **********
 
@@ -891,7 +893,6 @@
     return state;
 }
 
-
 /*********************************************************************//**
  * @brief
  * The handlePreTreatmentReservoirMgmtFillCmdState function sends fill
@@ -910,13 +911,20 @@
     {
         state = PRE_TREATMENT_RESERVOIR_MGMT_FILL_CMD_RESP_STATE;
 
-        if ( DG_RESERVOIR_1 == getDGInactiveReservoir() )
+        if ( ( TRUE == reservoirFlushedStatus[ DG_RESERVOIR_1 ] ) && ( TRUE == reservoirFlushedStatus[ DG_RESERVOIR_2 ] ) )
         {
-            cmdStartDGFill( PRE_TREATMENT_FILL_RESERVOIR_ONE_VOLUME_ML );
+            if ( DG_RESERVOIR_1 == getDGInactiveReservoir() )
+            {
+                cmdStartDGFill( PRE_TREATMENT_FILL_RESERVOIR_ONE_VOLUME_ML );
+            }
+            else
+            {
+                cmdStartDGFill( PRE_TREATMENT_FILL_RESERVOIR_TWO_VOLUME_ML );
+            }
         }
         else
         {
-            cmdStartDGFill( PRE_TREATMENT_FILL_RESERVOIR_TWO_VOLUME_ML );
+            cmdStartDGFill( PRE_TREATMENT_FLUSH_RESERVOIR_VOLUME_ML );
         }
     }
 
@@ -968,15 +976,33 @@
 
     if ( ( DG_MODE_CIRC == dgOpMode ) && ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode ) )
     {
-        if ( FALSE == reservoirFilledStatus[ DG_RESERVOIR_1 ] )
+        if ( ( TRUE == reservoirFlushedStatus[ DG_RESERVOIR_1 ] ) && ( TRUE == reservoirFlushedStatus[ DG_RESERVOIR_2 ] ) )
         {
-            state = PRE_TREATMENT_RESERVOIR_MGMT_WAIT_FOR_RESERVOIR_SWITCH_STATE;
-            reservoirFilledStatus[ DG_RESERVOIR_1 ] = TRUE;
+            if ( FALSE == reservoirFilledStatus[ DG_RESERVOIR_1 ] )
+            {
+                state = PRE_TREATMENT_RESERVOIR_MGMT_WAIT_FOR_RESERVOIR_SWITCH_STATE;
+                reservoirFilledStatus[ DG_RESERVOIR_1 ] = TRUE;
+            }
+            else if ( ( TRUE == reservoirFilledStatus[ DG_RESERVOIR_1 ] ) && ( FALSE == reservoirFilledStatus[ DG_RESERVOIR_2 ] ) )
+            {
+                reservoirFilledStatus[ DG_RESERVOIR_2 ] = TRUE;
+                state = PRE_TREATMENT_RESERVOIR_MGMT_COMPLETE_STATE;
+            }
         }
-        else if ( ( TRUE == reservoirFilledStatus[ DG_RESERVOIR_1 ] ) && ( FALSE == reservoirFilledStatus[ DG_RESERVOIR_2 ] ) )
+        else
         {
-            reservoirFilledStatus[ DG_RESERVOIR_2 ] = TRUE;
-            state = PRE_TREATMENT_RESERVOIR_MGMT_COMPLETE_STATE;
+            state = PRE_TREATMENT_RESERVOIR_MGMT_WAIT_FOR_RESERVOIR_SWITCH_STATE;
+
+            if ( FALSE == reservoirFlushedStatus[ DG_RESERVOIR_1 ] )
+            {
+                reservoirFlushedStatus[ DG_RESERVOIR_1 ] = TRUE;
+                cmdSetDGActiveReservoir( DG_RESERVOIR_1 );
+            }
+            else if ( ( TRUE == reservoirFlushedStatus[ DG_RESERVOIR_1 ] ) && ( FALSE == reservoirFlushedStatus[ DG_RESERVOIR_2 ] ) )
+            {
+                reservoirFlushedStatus[ DG_RESERVOIR_2 ] = TRUE;
+                cmdSetDGActiveReservoir( DG_RESERVOIR_2 );
+            }
         }
     }