Index: firmware/App/Modes/ModeFill.c
===================================================================
diff -u -r3acd796d26419a7290c6c18f0d48d9a992371e25 -rb41ffefac4fa72f8120849dd8a21af8f8c10948a
--- firmware/App/Modes/ModeFill.c	(.../ModeFill.c)	(revision 3acd796d26419a7290c6c18f0d48d9a992371e25)
+++ firmware/App/Modes/ModeFill.c	(.../ModeFill.c)	(revision b41ffefac4fa72f8120849dd8a21af8f8c10948a)
@@ -54,7 +54,7 @@
 #define RO_PUMP_800_ML_PER_MIN                          800.0F                                               ///< RO pump speed of 800.0 mL/minute.
 #define TARGET_RO_FLOW_RATE_IN_PAUSE_L                    0.8F                                               ///< Target flow rate for RO pump during pause in liters.
 #define MILLILITERS_PER_LITER                           1000.0F                                              ///< One liter is 1000 milliliters
-#define ACID_PUMP_20_ML_PER_MIN                         20.0F                                                ///< Acid pump speed of 20.0 mL/minute.
+#define ACID_PUMP_23_ML_PER_MIN                         23.0F                                                ///< Acid pump speed of 23.0 mL/minute.
 #define BICARB_PUMP_40_ML_PER_MIN                       40.0F                                                ///< Bicarb pump speed of 40.0 mL/minute.
 #define CONCENTRATE_PUMP_40_ML_PER_MIN                  40.0F                                                ///< Concentrate pump speed of 40.0 mL/minute.
 
@@ -758,18 +758,19 @@
         averageAcidConductivity   = totalAcidConductivity / acidConductivitySampleCount;
         pctDiffInConductivity     = fabs( 2.0F * ( averageAcidConductivity - averageBicarbConductivity ) /
                                                  ( averageAcidConductivity + averageBicarbConductivity ) );
-
-        SEND_EVENT_WITH_2_F32_DATA( DG_EVENT_ACID_CHECK_RESULT, averageAcidConductivity, acidCondUSPerCM )
+        // NOTE: CD2 or bicarb conductivity sensor is used for acid check since it is a more accurate sensor.
+        // CD2 is the downstream of the acid concentrate pump so the acid sensed there.
+        SEND_EVENT_WITH_2_F32_DATA( DG_EVENT_ACID_CHECK_RESULT, averageBicarbConductivity, acidCondUSPerCM )
         SEND_EVENT_WITH_2_F32_DATA( DG_EVENT_COND1_VS_COND2_DIFF_RESULT, pctDiffInConductivity, 0.0F )
 
-        if ( ( TRUE == isValueWithinPercentRange( averageAcidConductivity, acidCondUSPerCM, ACID_CHECK_TOL_FACTOR ) ) ||
+        if ( ( TRUE == isValueWithinPercentRange( averageBicarbConductivity, acidCondUSPerCM, ACID_CHECK_TOL_FACTOR ) ) ||
              ( TRUE == getTestConfigStatus( TEST_CONFIG_MIX_WITH_WATER ) ) )
         {
             hasAcidTestPassed = TRUE;
         }
         else
         {
-            SET_ALARM_WITH_2_F32_DATA( ALARM_ID_DG_ACID_CONDUCTIVITY_OUT_OF_RANGE, averageAcidConductivity, acidCondUSPerCM )
+            SET_ALARM_WITH_2_F32_DATA( ALARM_ID_DG_ACID_CONDUCTIVITY_OUT_OF_RANGE, averageBicarbConductivity, acidCondUSPerCM )
         }
 
         if ( ( pctDiffInConductivity < FIVE_PERCENT_FACTOR ) || ( TRUE == getTestConfigStatus( TEST_CONFIG_MIX_WITH_WATER ) ) )
@@ -1081,7 +1082,7 @@
             requestConcentratePumpOff( CONCENTRATEPUMPS_CP2_BICARB, NO_PARK_CONC_PUMPS );
             // Set pumps flow rate to prepare for acid conductivity testing
             setROPumpTargetFlowRateLPM( RO_PUMP_800_ML_PER_MIN / MILLILITERS_PER_LITER, TARGET_RO_PRESSURE_PSI );
-            setConcentratePumpTargetSpeed( CONCENTRATEPUMPS_CP1_ACID, ACID_PUMP_20_ML_PER_MIN );
+            setConcentratePumpTargetSpeed( CONCENTRATEPUMPS_CP1_ACID, ACID_PUMP_23_ML_PER_MIN );
             requestConcentratePumpOn( CONCENTRATEPUMPS_CP1_ACID );
 
             // Set back the conductivity of CD2 calibration table to the normal calibration table