Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -r9feea867113c62088f0ce91750127972dbd9bf53 -r44a100f8e5210a02c23b8fcc4527d8e96d577381
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 9feea867113c62088f0ce91750127972dbd9bf53)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 44a100f8e5210a02c23b8fcc4527d8e96d577381)
@@ -16,13 +16,15 @@
 ***************************************************************************/
 
 #include "DialInFlow.h"
+#include "Dialysis.h"
 #include "DGDefs.h"
+#include "DGInterface.h"
 #include "ModeInitPOST.h"
-#include "ModeTreatment.h"
+#include "ModeTreatment.h"
+#include "ModeTreatmentParams.h"
 #include "OperationModes.h"
 #include "SystemCommMessages.h"
 #include "Timers.h"
-#include "DGInterface.h"
 
 /**
  *  @addtogroup DGInterface
@@ -36,6 +38,8 @@
 
 #define RESERVOIR_SETTLE_TIME_MS            5000                ///< Time (in ms) allotted for reservoir to settle (after fill, before drain).
 
+#define MAX_RESERVOIR_VOLUME_ML             1950.0              ///< Maximum reservoir volume.  Switch reservoirs if active reservoir exceeds this volume.
+
 #define SIZE_OF_LARGE_LOAD_CELL_AVG         32                  ///< Large load cell moving average has 32 samples.
 
 /// States of the treatment reservoir management state machine.
@@ -226,6 +230,19 @@
     }
     resUseTimer = getMSTimerCount();
 
+    // Alarm if active reservoir is full and inactive reservoir is not yet ready
+    if ( getReservoirWeight( getDGActiveReservoir() ) > MAX_RESERVOIR_VOLUME_ML )
+    {
+        if ( currentTrtResMgmtState < TREATMENT_RESERVOIR_MGMT_WAIT_FOR_RES_SWITCH_STATE )
+        {
+            SET_ALARM_WITH_2_F32_DATA( ALARM_ID_HD_RESERVOIR_FULL_AND_DG_NOT_READY_TO_SWITCH, getReservoirWeight( getDGActiveReservoir() ), (F32)currentTrtResMgmtState )
+        }
+        else
+        {
+            clearAlarmCondition( ALARM_ID_HD_RESERVOIR_FULL_AND_DG_NOT_READY_TO_SWITCH );
+        }
+    }
+
     // Treatment reservoir mgmt. state machine
     switch ( currentTrtResMgmtState )
     {
@@ -265,8 +282,14 @@
                 if ( DG_MODE_CIRC == dgOpMode )
                 {
                     if ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode )
-                    {
-                        cmdStartDGFill( FILL_RESERVOIR_TO_VOLUME_ML );
+                    {
+                        U32 fillToVolume = FILL_RESERVOIR_TO_VOLUME_ML;
+
+                        if ( getTreatmentParameterU32( TREATMENT_PARAM_DIALYSATE_FLOW ) <= SLOW_DIALYSATE_FLOW_ML_MIN )
+                        {
+                            fillToVolume = FILL_RESERVOIR_TO_VOLUME_LOW_FLOW_ML;
+                        }
+                        cmdStartDGFill( fillToVolume );
                     }
                 }
                 else
@@ -297,9 +320,8 @@
 
         case TREATMENT_RESERVOIR_MGMT_WAIT_FOR_RES_SWITCH_STATE:
             // Reservoir switch during treatment should only occur in this state (i.e. when DG is ready).
-            // Switch reservoirs when active reservoir is spent (i.e. we have pumped fill volume through dialyzer) and DG ready
-            if ( ( DG_MODE_CIRC == getDGOpMode() ) && ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == getDGSubMode() ) &&
-                  ( resUseVolumeMl >= (F32)dgReservoirFillVolumeTargetSet ) )
+            // Switch reservoirs when active reservoir is spent or full (i.e. we have pumped fill volume through dialyzer) and DG ready
+            if ( ( resUseVolumeMl >= (F32)dgReservoirFillVolumeTargetSet ) || ( getReservoirWeight( getDGActiveReservoir() ) > MAX_RESERVOIR_VOLUME_ML ) )
             {
                 DG_RESERVOIR_ID_T inactiveRes = getDGInactiveReservoir();
 
@@ -518,6 +540,23 @@
     return result;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The getReservoirWeight function gets the load cell weight of a given
+ * reservoir.
+ * @details Inputs: loadCellWeightInGrams[]
+ * @details Outputs: none
+ * @param resID ID of reservoir to get weight for
+ * @return the current weight of the given reservoir in grams
+ *************************************************************************/
+F32 getReservoirWeight( DG_RESERVOIR_ID_T resID )
+{
+    LOAD_CELL_ID_T lc = ( DG_RESERVOIR_1 == resID ? LOAD_CELL_RESERVOIR_1_PRIMARY : LOAD_CELL_RESERVOIR_2_PRIMARY );
+    F32 wt = getLoadCellWeight( lc );
+
+    return wt;
+}
+
 /*********************************************************************//**
  * @brief
  * The setDGOpMode function sets the latest DG operating mode reported by
@@ -670,7 +709,7 @@
     loadCellWeightInGrams[ LOAD_CELL_RESERVOIR_2_PRIMARY ].data = res2Primary;
     loadCellWeightInGrams[ LOAD_CELL_RESERVOIR_2_BACKUP ].data = res2Backup;
 
-    // feed new weight samples into filters and update moving averages
+    // Feed new weight samples into filters and update moving averages
     for ( res = DG_RESERVOIR_1; res < NUM_OF_DG_RESERVOIRS; res++ )
     {
         F32  wt = ( res == DG_RESERVOIR_1 ? res1Primary : res2Primary );
@@ -680,6 +719,9 @@
         lgFilteredReservoirWeightInGrams[ res ] = lgLoadCellReadingsTotal[ res ] / (F32)SIZE_OF_LARGE_LOAD_CELL_AVG;
     }
     lgLoadCellReadingsIdx = INC_WRAP( lgLoadCellReadingsIdx, 0, SIZE_OF_LARGE_LOAD_CELL_AVG - 1 );
+
+    // Update Dialysis sub-mode with new reservoir volumes
+    updateReservoirVolumes( res1Primary, res2Primary );
 }
 
 /*********************************************************************//**