Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -r4b22b45e775c0525bc1d76e83e265af91a59785e -r47a7da55aea88cd7a2b06870226122d0cc8be540
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 4b22b45e775c0525bc1d76e83e265af91a59785e)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 47a7da55aea88cd7a2b06870226122d0cc8be540)
@@ -31,9 +31,6 @@
 #define START_DG_CMD                        TRUE                ///< Parameter for DG start/stop command function.  True = start.
 #define STOP_DG_CMD                         FALSE               ///< Parameter for DG start/stop command function.  False = stop.
 
-#define DRAIN_RESERVOIR_TO_VOLUME_ML        200 //100                 ///< Drain reservoir to this volume (in mL) during treatment.
-#define FILL_RESERVOIR_TO_VOLUME_ML         1500                ///< Fill reservoir to this volume (in mL) during treatment.
-
 #define RESERVOIR_SETTLE_TIME_MS            5000                ///< Time (in ms) allotted for reservoir to settle (after fill, before drain).
 
 /// States of the treatment reservoir management state machine.
Index: firmware/App/Controllers/DGInterface.h
===================================================================
diff -u -r2df21d2472a8d79d78af7e359518acf3614accc5 -r47a7da55aea88cd7a2b06870226122d0cc8be540
--- firmware/App/Controllers/DGInterface.h	(.../DGInterface.h)	(revision 2df21d2472a8d79d78af7e359518acf3614accc5)
+++ firmware/App/Controllers/DGInterface.h	(.../DGInterface.h)	(revision 47a7da55aea88cd7a2b06870226122d0cc8be540)
@@ -31,6 +31,9 @@
 
 // ********** public definitions **********
 
+#define DRAIN_RESERVOIR_TO_VOLUME_ML        200 //100                 ///< Drain reservoir to this volume (in mL) during treatment.
+#define FILL_RESERVOIR_TO_VOLUME_ML         1700                ///< Fill reservoir to this volume (in mL) during treatment.
+
 /// Enumeration of DG reservoirs.
 typedef enum DG_Reservoirs
 {
Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -r7fa65a3aae9c4ef70a6e53f3e3bb20f0425bd681 -r47a7da55aea88cd7a2b06870226122d0cc8be540
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 7fa65a3aae9c4ef70a6e53f3e3bb20f0425bd681)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 47a7da55aea88cd7a2b06870226122d0cc8be540)
@@ -121,7 +121,7 @@
             {
                 if ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode )
                 {
-                    cmdStartDGDrain( 200 );
+                    cmdStartDGDrain( DRAIN_RESERVOIR_TO_VOLUME_ML );
                 }
             }
             else if ( DG_MODE_DRAI == dgOpMode )
@@ -148,7 +148,7 @@
             {
                 if ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode )
                 {
-                    cmdStartDGFill( 1700 );  // TODO - define this in pre-treatment mode when implemented.
+                    cmdStartDGFill( FILL_RESERVOIR_TO_VOLUME_ML );
                 }
             }
             else if ( DG_MODE_FILL == dgOpMode )
Index: firmware/App/Modes/ModeTreatment.c
===================================================================
diff -u -r12ae81f766052993995d323456fa4c746cf4ee75 -r47a7da55aea88cd7a2b06870226122d0cc8be540
--- firmware/App/Modes/ModeTreatment.c	(.../ModeTreatment.c)	(revision 12ae81f766052993995d323456fa4c746cf4ee75)
+++ firmware/App/Modes/ModeTreatment.c	(.../ModeTreatment.c)	(revision 47a7da55aea88cd7a2b06870226122d0cc8be540)
@@ -708,19 +708,17 @@
         U32 maxTime2 = MAX_DIALYSATE_VOLUME_ML / presDialysateFlowRate;
         U32 maxTime = MIN( maxTime1, maxTime2 );
         // compute minimum UF volume
-        U32 minUFVol = (U32)(getUltrafiltrationVolumeCollected());
-        // compute maximum UF volume (considering from adjustment of treatment duration or UF rate perspectives)
-        U32 maxUFVol1 = minUFVol + ( ( CALC_TREAT_TIME_REMAINING_IN_SECS() / SEC_PER_MIN ) * MAX_UF_RATE_ML_MIN );
-        U32 maxUFVol2 = ( presUFRate > 0 ? minUFVol + (U32)( ( MAX_TREATMENT_TIME_MINUTES - CALC_ELAPSED_TREAT_TIME_IN_MIN() - 1 ) * presUFRate ) : MAX_UF_VOLUME_ML );
-        U32 maxUFVol = MIN( maxUFVol1, maxUFVol2 );
+        F32 minUFVol = getUltrafiltrationVolumeCollected() + presUFRate;
+        // compute maximum UF volume (considering from adjustment of UF rate perspective)
+        F32 maxUFVol = ( presUFRate > 0.0 ? minUFVol + ( (F32)( MAX_TREATMENT_TIME_MINUTES - CALC_ELAPSED_TREAT_TIME_IN_MIN() - 1 ) * presUFRate ) : (F32)MAX_UF_VOLUME_ML );
         // compute minimum dialysate flow rate
         U32 minDialRate = MIN_DIAL_IN_FLOW_RATE;
         // compute maximum dialysate flow rate from max dialysate volume perspective
         U32 maxDialRate = MAX_DIALYSATE_VOLUME_ML / ( presTreatmentTimeSecs / SEC_PER_MIN );
 
         // now ensure maximums do not exceed the literal maximums
         maxTime = MIN( maxTime, MAX_TREATMENT_TIME_MINUTES );
-        maxUFVol = MIN( maxUFVol, MAX_UF_VOLUME_ML );
+        maxUFVol = MIN( maxUFVol, (F32)MAX_UF_VOLUME_ML );
         maxDialRate = MIN( maxDialRate, MAX_DIAL_IN_FLOW_RATE );
         // send updated treatment parameter ranges to UI
         sendTreatmentParamsRangesToUI( minTime, maxTime, minUFVol, maxUFVol, minDialRate, maxDialRate );
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r6e8917e48113a8798b26e489296a3f69509c0590 -r47a7da55aea88cd7a2b06870226122d0cc8be540
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 6e8917e48113a8798b26e489296a3f69509c0590)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 47a7da55aea88cd7a2b06870226122d0cc8be540)
@@ -340,7 +340,6 @@
 BOOL sendChangeUFSettingsResponse( BOOL accepted, U32 reason, F32 volume_mL, U32 time_min, F32 ufRate_mL_min, S32 timeDiff, F32 rateDiff, F32 oldUFRate_mL_min )
 {
     BOOL result;
-    F32 volume_L = volume_mL / (F32)ML_PER_LITER;
     MESSAGE_T msg;
     U08 *payloadPtr = msg.payload;
 
@@ -353,7 +352,7 @@
     payloadPtr += sizeof( BOOL );
     memcpy( payloadPtr, &reason, sizeof( U32) );
     payloadPtr += sizeof( U32 );
-    memcpy( payloadPtr, &volume_L, sizeof( F32 ) );
+    memcpy( payloadPtr, &volume_mL, sizeof( F32 ) );
     payloadPtr += sizeof( F32 );
     memcpy( payloadPtr, &time_min, sizeof( U32 ) );
     payloadPtr += sizeof( U32 );
@@ -389,7 +388,6 @@
 BOOL sendChangeUFSettingsOptionResponse( BOOL accepted, U32 reason, F32 volume_mL, U32 time_min, F32 ufRate_mL_min )
 {
     BOOL result;
-    F32 volume_L = volume_mL / (F32)ML_PER_LITER;
     MESSAGE_T msg;
     U08 *payloadPtr = msg.payload;
 
@@ -402,7 +400,7 @@
     payloadPtr += sizeof( BOOL );
     memcpy( payloadPtr, &reason, sizeof( U32) );
     payloadPtr += sizeof( U32 );
-    memcpy( payloadPtr, &volume_L, sizeof( F32 ) );
+    memcpy( payloadPtr, &volume_mL, sizeof( F32 ) );
     payloadPtr += sizeof( F32 );
     memcpy( payloadPtr, &time_min, sizeof( U32 ) );
     payloadPtr += sizeof( U32 );
@@ -431,7 +429,6 @@
 BOOL sendChangeTreatmentDurationResponse( BOOL accepted, U32 reason, U32 time_min, F32 volume_mL )
 {
     BOOL result;
-    F32 volume_L = volume_mL / (F32)ML_PER_LITER;
     MESSAGE_T msg;
     U08 *payloadPtr = msg.payload;
 
@@ -446,7 +443,7 @@
     payloadPtr += sizeof( U32 );
     memcpy( payloadPtr, &time_min, sizeof( U32 ) );
     payloadPtr += sizeof( U32 );
-    memcpy( payloadPtr, &volume_L, sizeof( F32 ) );
+    memcpy( payloadPtr, &volume_mL, sizeof( F32 ) );
 
     // 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_UI, ACK_REQUIRED );
@@ -508,7 +505,7 @@
  * @param maxDialRate : Maximum dialysate flow rate (in mL/min).
  * @return TRUE if msg successfully queued for transmit, FALSE if not
  *************************************************************************/
-BOOL sendTreatmentParamsRangesToUI( U32 minTime, U32 maxTime, U32 minUFVol, U32 maxUFVol, U32 minDialRate, U32 maxDialRate )
+BOOL sendTreatmentParamsRangesToUI( U32 minTime, U32 maxTime, F32 minUFVol, F32 maxUFVol, U32 minDialRate, U32 maxDialRate )
 {
     BOOL result;
     MESSAGE_T msg;
@@ -517,16 +514,16 @@
     // create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_TREATMENT_PARAM_CHANGE_RANGES;
-    msg.hdr.payloadLen = sizeof( U32 ) + sizeof( U32 ) + sizeof( U32 ) + sizeof( U32 ) + sizeof( U32 ) + sizeof( U32 );
+    msg.hdr.payloadLen = sizeof( U32 ) + sizeof( U32 ) + sizeof( F32 ) + sizeof( F32 ) + sizeof( U32 ) + sizeof( U32 );
 
     memcpy( payloadPtr, &minTime, sizeof( U32 ) );
     payloadPtr += sizeof( U32 );
     memcpy( payloadPtr, &maxTime, sizeof( U32 ) );
     payloadPtr += sizeof( U32 );
-    memcpy( payloadPtr, &minUFVol, sizeof( U32 ) );
-    payloadPtr += sizeof( U32 );
-    memcpy( payloadPtr, &maxUFVol, sizeof( U32 ) );
-    payloadPtr += sizeof( U32 );
+    memcpy( payloadPtr, &minUFVol, sizeof( F32 ) );
+    payloadPtr += sizeof( F32 );
+    memcpy( payloadPtr, &maxUFVol, sizeof( F32 ) );
+    payloadPtr += sizeof( F32 );
     memcpy( payloadPtr, &minDialRate, sizeof( U32 ) );
     payloadPtr += sizeof( U32 );
     memcpy( payloadPtr, &maxDialRate, sizeof( U32 ) );
Index: firmware/App/Services/SystemCommMessages.h
===================================================================
diff -u -r12ae81f766052993995d323456fa4c746cf4ee75 -r47a7da55aea88cd7a2b06870226122d0cc8be540
--- firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision 12ae81f766052993995d323456fa4c746cf4ee75)
+++ firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision 47a7da55aea88cd7a2b06870226122d0cc8be540)
@@ -79,7 +79,7 @@
 BOOL sendChangeTreatmentDurationResponse( BOOL accepted, U32 reason, U32 time_min, F32 volume_mL );
 
 // MSG_ID_TREATMENT_PARAM_CHANGE_RANGES
-BOOL sendTreatmentParamsRangesToUI( U32 minTime, U32 maxTime, U32 minUFVol, U32 maxUFVol, U32 minDialRate, U32 maxDialRate );
+BOOL sendTreatmentParamsRangesToUI( U32 minTime, U32 maxTime, F32 minUFVol, F32 maxUFVol, U32 minDialRate, U32 maxDialRate );
 
 // MSG_ID_USER_BLOOD_DIAL_RATE_CHANGE_REQUEST
 void handleChangeBloodDialysateRateChangeRequest( MESSAGE_T *message );