Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -r1a685471524555a374854c0c9ec8e208e71fe2df -rf94085c6fbf817a07db7225d6748b5347dfb12d3
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 1a685471524555a374854c0c9ec8e208e71fe2df)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision f94085c6fbf817a07db7225d6748b5347dfb12d3)
@@ -157,7 +157,7 @@
             {
                 if ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode )
                 {
-                    cmdStartDGDrain( DRAIN_RESERVOIR_TO_VOLUME_ML );
+                    cmdStartDGDrain( DRAIN_RESERVOIR_TO_VOLUME_ML, FALSE );
                 }
             }
             else if ( DG_MODE_DRAI == dgOpMode )
@@ -599,14 +599,19 @@
  * @brief
  * The cmdStartDGDrain function sends a drain command message to the DG.
  * @details Inputs: none
- * @details Outputs: drain command sent to DG.
- * @param drainToVolMl volume (in mL) to drain inactive reservoir to
+ * @details Outputs: drain command sent to DG.
+ * @param drainToVolMl volume (in mL) to drain inactive reservoir to
+ * @param tareLoadCell flag to tell DG tare load cell or not
  * @return none
  *************************************************************************/
-void cmdStartDGDrain( U32 drainToVolMl )
-{
+void cmdStartDGDrain( U32 drainToVolMl, BOOL tareLoadCell )
+{
+    DRAIN_RESERVOIR_CMD_PAYLOAD_T payload;
+
+    payload.drainToVolumeML = drainToVolMl;
+    payload.tareLoadCells = tareLoadCell;
     dgReservoirDrainVolumeTargetSet = drainToVolMl;
-    sendDGDrainCommand( drainToVolMl );
+    sendDGDrainCommand( &payload );
 }
 
 /*********************************************************************//**
Index: firmware/App/Controllers/DGInterface.h
===================================================================
diff -u -rb01542f8e4ef5a29e9b08fc0d465478de516bf02 -rf94085c6fbf817a07db7225d6748b5347dfb12d3
--- firmware/App/Controllers/DGInterface.h	(.../DGInterface.h)	(revision b01542f8e4ef5a29e9b08fc0d465478de516bf02)
+++ firmware/App/Controllers/DGInterface.h	(.../DGInterface.h)	(revision f94085c6fbf817a07db7225d6748b5347dfb12d3)
@@ -106,6 +106,13 @@
     F32 HtrTrimInternal;
 } DG_TEMPERATURES_T;
 
+/// Payload record structure for a drain reservoir command message.
+typedef struct
+{
+    U32  drainToVolumeML;
+    BOOL tareLoadCells;
+} DRAIN_RESERVOIR_CMD_PAYLOAD_T;
+
 // ********** public function prototypes **********
 
 void initDGInterface( void );
@@ -133,7 +140,7 @@
 void cmdStopDG( void );
 void cmdSetDGActiveReservoir( DG_RESERVOIR_ID_T resID );
 void cmdStartDGFill( U32 fillToVolMl );
-void cmdStartDGDrain( U32 drainToVolMl );
+void cmdStartDGDrain( U32 drainToVolMl, BOOL tareLoadCell );
 void cmdStartDGTrimmerHeater( void );
 void cmdStopDGTrimmerHeater( void );
 void cmdDGSampleWater( void );
Index: firmware/App/Modes/Prime.c
===================================================================
diff -u -r5c521c4e9f0840c337133dc041f5e61bc89353ea -rf94085c6fbf817a07db7225d6748b5347dfb12d3
--- firmware/App/Modes/Prime.c	(.../Prime.c)	(revision 5c521c4e9f0840c337133dc041f5e61bc89353ea)
+++ firmware/App/Modes/Prime.c	(.../Prime.c)	(revision f94085c6fbf817a07db7225d6748b5347dfb12d3)
@@ -187,7 +187,7 @@
         case PRIME_RESERVOIR_MGMT_FLUSH_DG_LINES_STATE:
             if ( ( DG_MODE_CIRC == dgOpMode ) && ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode ) )
             {
-                cmdStartDGDrain( PRIME_DRAIN_RESERVOIR_TO_VOLUME_ML );
+                cmdStartDGDrain( PRIME_DRAIN_RESERVOIR_TO_VOLUME_ML, TRUE );
             }
 
             if ( DG_MODE_DRAI == dgOpMode )
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r780d9a73fe04ddd85282c413fbe5984f374f2b61 -rf94085c6fbf817a07db7225d6748b5347dfb12d3
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 780d9a73fe04ddd85282c413fbe5984f374f2b61)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision f94085c6fbf817a07db7225d6748b5347dfb12d3)
@@ -569,7 +569,7 @@
  * @param drainToVolumeMl volume (in mL) to drain the inactive reservoir to
  * @return TRUE if msg successfully queued for transmit, FALSE if not
  *************************************************************************/
-BOOL sendDGDrainCommand( U32 drainToVolumeMl )
+BOOL sendDGDrainCommand( DRAIN_RESERVOIR_CMD_PAYLOAD_T *drainCmdPtr )
 {
     BOOL result;
     MESSAGE_T msg;
@@ -578,9 +578,9 @@
     // create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_DRAIN_CMD;
-    msg.hdr.payloadLen = sizeof( U32 );
+    msg.hdr.payloadLen = sizeof( DRAIN_RESERVOIR_CMD_PAYLOAD_T );
 
-    memcpy( payloadPtr, &drainToVolumeMl, sizeof( U32 ) );
+    memcpy( payloadPtr, drainCmdPtr, sizeof( DRAIN_RESERVOIR_CMD_PAYLOAD_T ) );
 
     // serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
     result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_HD_2_DG, ACK_REQUIRED );
Index: firmware/App/Services/SystemCommMessages.h
===================================================================
diff -u -r933a18d740285e70be9d00696ed0f5a5381bc8e4 -rf94085c6fbf817a07db7225d6748b5347dfb12d3
--- firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision 933a18d740285e70be9d00696ed0f5a5381bc8e4)
+++ firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision f94085c6fbf817a07db7225d6748b5347dfb12d3)
@@ -160,7 +160,7 @@
 BOOL sendDGFillCommand( U32 fillToVolumeMl );
 
 // MSG_ID_DG_DRAIN_CMD
-BOOL sendDGDrainCommand( U32 drainToVolumeMl );
+BOOL sendDGDrainCommand( DRAIN_RESERVOIR_CMD_PAYLOAD_T *drainCmdPtr );
 
 // MSG_ID_STARTING_STOPPING_TREATMENT_CMD
 BOOL sendDGStartStopCommand( BOOL start );