Index: firmware/App/Modes/FPModes/FlushPermeate.c
===================================================================
diff -u -recb538c8bf67a7a62d11a1186a9ef5fe53cf9d9e -r97f657d47a01b765b72e5193c434dd959c3a3f35
--- firmware/App/Modes/FPModes/FlushPermeate.c	(.../FlushPermeate.c)	(revision ecb538c8bf67a7a62d11a1186a9ef5fe53cf9d9e)
+++ firmware/App/Modes/FPModes/FlushPermeate.c	(.../FlushPermeate.c)	(revision 97f657d47a01b765b72e5193c434dd959c3a3f35)
@@ -42,6 +42,7 @@
 #define PERMEATE_FLUSH_RO_PUMP_TGT_ML               700                                         ///< Pressure target in ml/min for the RO pump during permeate flush.
 #define PERMEATE_FLUSH_BOOST_PUMP_TGT_PSI           25                                          ///< Pressure target in PSI for the boost pump during permeate flush.
 #define PERMEATE_FLUSH_CONDUCTIVITY_THRESHOLD       200.0F                                      ///< Conductivity alarm threshold for permeate flush.
+#define MIN_BOOST_PUMP_DUTY_CYCLE_PCT               0.5F                                        ///< Minimum duty cycle value for boost pump during open loop control
 
 // ********** private data **********
 
@@ -54,6 +55,7 @@
 static U32 permeateFlushAlarmTimer;
 static BOOL pendingStartPermeateFlushRequest;                                                   ///< signal to start flushing.
 static BOOL isFlushComplete;                                                                    ///< Permeate Flush complete BOOL
+static BOOL isTankFilled;                                                                       ///< Permeate tank filled in permeate flush state
 
 // ********** private function prototypes **********
 
@@ -92,6 +94,7 @@
     permeateFlushAlarmTimer                          = 0;
     isFlushComplete                                  = FALSE;
     pendingStartPermeateFlushRequest                 = FALSE;
+    isTankFilled                                     = FALSE;
 }
 
 /*********************************************************************//**
@@ -153,16 +156,29 @@
     if ( LEVEL_STATE_HIGH == level )
     {
         setValveState( M4_VALV, VALVE_STATE_CLOSED );
+        if ( TRUE == isBoostPumpInstalled() )
+        {
+            F32 currentDutyCyclePct = getCurrentBoostPumpDutyCyclePCT() > MIN_BOOST_PUMP_DUTY_CYCLE_PCT ? getCurrentBoostPumpDutyCyclePCT(): MIN_BOOST_PUMP_DUTY_CYCLE_PCT;
+
+            setBoostPumpTargetDutyCycle( currentDutyCyclePct  );
+            isTankFilled = TRUE;
+        }
     }
     else if ( LEVEL_STATE_LOW == level )
     {
         setValveState( M4_VALV, VALVE_STATE_OPEN );
+        // set boost pump to closed loop when M4 closed. Added Tank fill check to avoid reset during initial transition
+        if ( ( TRUE == isBoostPumpInstalled() ) && ( TRUE == isTankFilled ) )
+        {
+            setBoostPumpTargetPressure( PERMEATE_FLUSH_BOOST_PUMP_TGT_PSI );
+            isTankFilled = FALSE;
+        }
     }
 
     if( TRUE == didTimeout( permeateFlushTimer, getPermeateFlushTimeout() ) )
     {
         F32 p18conductivity = getFilteredConductivity( P18_COND );
-        if( PERMEATE_FLUSH_CONDUCTIVITY_THRESHOLD > p18conductivity )
+        if( PERMEATE_FLUSH_CONDUCTIVITY_THRESHOLD > p18conductivity && ( LEVEL_STATE_HIGH == level ) )
         {
             isFlushComplete = TRUE;
             state = PERM_FLUSH_PAUSED;