Index: firmware/App/Modes/ModeGenDialysate.c
===================================================================
diff -u -r2d295ca85f19e95da42476a57ca6b4496baf980a -r8348015aa77e1ee2c4c20e9f8e2c45b59bcf3f17
--- firmware/App/Modes/ModeGenDialysate.c	(.../ModeGenDialysate.c)	(revision 2d295ca85f19e95da42476a57ca6b4496baf980a)
+++ firmware/App/Modes/ModeGenDialysate.c	(.../ModeGenDialysate.c)	(revision 8348015aa77e1ee2c4c20e9f8e2c45b59bcf3f17)
@@ -655,20 +655,25 @@
 
 /*********************************************************************//**
  * @brief
- * The getCalculatedD48PumpSpeedForBCFill function returns the D48 pump speed
- * calculated from dialysate flow rate (Qd) for continuous delivery.
- * @details \b Inputs: Qd from TD, test config TEST_CONFIG_DD_ENABLE_DIENER_1000_PUMP.
+ * The getNominalD48PumpSpeedCeiledForBCFill function returns the ceiled D48
+ * pump speed from the Diener formula before any low-speed clamp.
+ * @details \b Inputs: Active BC Qd (or TD Qd before BC period init), pump test config.
  * @details \b Outputs: none
- * @return Calculated D48 pump speed in RPM (Diener 1000 or 2000 formula per test config).
+ * @return Nominal D48 pump speed in RPM (ceil of formula output).
  *************************************************************************/
-U32 getCalculatedD48PumpSpeedForBCFill( void )
+U32 getNominalD48PumpSpeedCeiledForBCFill( void )
 {
-    F32 dialFlowrate = getTDDialysateFlowrate();
+    F32 dialFlowrate = getBalChamberActiveDialysateFlowrate();
     F32 slope;
     F32 intercept;
     F32 calculatedSpeed;
     U32 rpm;
 
+    if ( 0U == getBalChamberSwitchingPeriod() )
+    {
+        dialFlowrate = getTDDialysateFlowrate();
+    }
+
     if ( TRUE == getTestConfigStatus( TEST_CONFIG_DD_ENABLE_DIENER_2000_PUMP ) )
     {
         slope     = PUMP_SPEED_SLOPE_FACTOR_DIENER_2000;
@@ -680,10 +685,8 @@
         intercept = PUMP_SPEED_INTERCEPT_FACTOR_DIENER_1000;
     }
 
-    // Calculate nominal speed from Qd.
     calculatedSpeed = ( slope * dialFlowrate ) + intercept;
 
-    // Prevent negative before converting to unsigned and round up using ceilf.
     if ( calculatedSpeed < 0.0F )
     {
         calculatedSpeed = 0.0F;
@@ -696,6 +699,30 @@
 
 /*********************************************************************//**
  * @brief
+ * The getCalculatedD48PumpSpeedForBCFill function returns the D48 pump speed
+ * for balancing chamber fill after applying the low-speed clamp.
+ * @details \b Inputs: Active BC Qd (or TD Qd before BC period init), pump test config.
+ * @details \b Outputs: none
+ * @return D48 pump speed in RPM for BC fill (Diener formula with low-speed floor).
+ *************************************************************************/
+U32 getCalculatedD48PumpSpeedForBCFill( void )
+{
+    U32 rpm;
+    U32 nominalRpm;
+
+    nominalRpm = getNominalD48PumpSpeedCeiledForBCFill();
+    rpm        = nominalRpm;
+
+    if ( nominalRpm <= BAL_CHAMBER_TIME_BASED_D48_SPEED_RPM )
+    {
+        rpm = BAL_CHAMBER_TIME_BASED_D48_SPEED_RPM;
+    }
+
+    return rpm;
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleGenDDialysateIsolatedUFState function performs the
  * Isolated ultrafiltration operations.
  * @details \b Inputs: none.