Index: firmware/App/Controllers/FluidLeak.c
===================================================================
diff -u -r9d924ec76ce770eb2a94088bfe37bfb0e30981a8 -r04717003bb672ca3ed507a924156e141db2d5855
--- firmware/App/Controllers/FluidLeak.c	(.../FluidLeak.c)	(revision 9d924ec76ce770eb2a94088bfe37bfb0e30981a8)
+++ firmware/App/Controllers/FluidLeak.c	(.../FluidLeak.c)	(revision 04717003bb672ca3ed507a924156e141db2d5855)
@@ -19,6 +19,7 @@
 #include "FluidLeak.h"
 #include "FPGA.h"
 #include "OperationModes.h"
+#include "PersistentAlarm.h"
 #include "SystemCommMessages.h"
 #include "TaskPriority.h"
 #include "Timers.h"
@@ -33,6 +34,9 @@
 #define FLUID_LEAK_PUB_INTERVAL           ( MS_PER_SECOND / TASK_PRIORITY_INTERVAL )        ///< Interval (ms/task time) at which the fluid leak data is published on the CAN bus.
 #define DATA_PUBLISH_COUNTER_START_COUNT  50                                                ///< Data publish counter start count.
 
+/// Persist time (in ms) for fluid leak error condition.
+static const U32 FLUID_LEAK_ERROR_PERSIST_MS  = 250;
+
 // ********** private data **********
 
 static U32 fluidLeakStatePublicationTimerCounter;                                           ///< Timer counter used to schedule fluid leak publication to CAN bus.
@@ -59,6 +63,8 @@
     fluidLeakState.ovData                 = FLUID_LEAK_STATE_DRY;
     fluidLeakState.override               = OVERRIDE_RESET;
     fluidLeakStatePublicationTimerCounter = DATA_PUBLISH_COUNTER_START_COUNT;
+
+    initPersistentAlarm( ALARM_ID_HD_FLUID_LEAK_DETECTED, 0, FLUID_LEAK_ERROR_PERSIST_MS );
 }
 
 /*********************************************************************//**
@@ -87,10 +93,14 @@
         // Check state reading and act upon
         if ( FLUID_LEAK_STATE_WET == getFluidLeakState() )
         {
-            activateAlarmNoData( ALARM_ID_HD_FLUID_LEAK_DETECTED );
+            if ( TRUE == isPersistentAlarmTriggered( ALARM_ID_HD_FLUID_LEAK_DETECTED, TRUE ) )
+            {
+                activateAlarmNoData( ALARM_ID_HD_FLUID_LEAK_DETECTED );
+            }
         }
         else // FLUID_LEAK_STATE_DRY == getFluidLeakState()
         {
+            isPersistentAlarmTriggered( ALARM_ID_HD_FLUID_LEAK_DETECTED, FALSE );
             clearAlarmCondition( ALARM_ID_HD_FLUID_LEAK_DETECTED );
         }
     }
Index: firmware/App/Modes/ModeTreatmentParams.h
===================================================================
diff -u -r99ec83eff4683ad69a249f935d74cb9226984d21 -r04717003bb672ca3ed507a924156e141db2d5855
--- firmware/App/Modes/ModeTreatmentParams.h	(.../ModeTreatmentParams.h)	(revision 99ec83eff4683ad69a249f935d74cb9226984d21)
+++ firmware/App/Modes/ModeTreatmentParams.h	(.../ModeTreatmentParams.h)	(revision 04717003bb672ca3ed507a924156e141db2d5855)
@@ -34,7 +34,7 @@
 
 #define MIN_PRESSURE_ALARM_LIMIT_DELTA_MMHG     ( 30 )                                      ///< Minimum pressure alarm limit delta (in mmHg)
 #define MAX_UF_RATE_ML_MIN                      ( 2500.01F / (F32)MIN_PER_HOUR )            ///< Maximum ultrafiltration rate (in mL/min).  Added small decimal to prevent float round off issues.
-#define MIN_UF_RATE_ML_MIN                      ( 100.0F / (F32)MIN_PER_HOUR )              ///< Minimum ultrafiltration rate (in mL/min).
+#define MIN_UF_RATE_ML_MIN                      ( 0.0F )                                    ///< Minimum ultrafiltration rate (in mL/min).
 #define MAX_UF_VOLUME_ML                        ( 8 * ML_PER_LITER )                        ///< Maximum ultrafiltration volume (in mL).
 
 /// Record structure for a treatment parameters payload.
Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -rbb43bcd42a48f6e754d1a6b0f346e9a876d6dcf6 -r04717003bb672ca3ed507a924156e141db2d5855
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision bb43bcd42a48f6e754d1a6b0f346e9a876d6dcf6)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 04717003bb672ca3ed507a924156e141db2d5855)
@@ -53,7 +53,7 @@
 
 #define MSG_NOT_ACKED_TIMEOUT_MS        150     ///< Maximum time for a Denali message that requires ACK to be ACK'd
 
-#define MSG_NOT_ACKED_MAX_RETRIES       8       ///< Maximum number of times a message that requires ACK that was not ACK'd can be re-sent before alarm
+#define MSG_NOT_ACKED_MAX_RETRIES       10      ///< Maximum number of times a message that requires ACK that was not ACK'd can be re-sent before alarm
 #define PENDING_ACK_LIST_SIZE           25      ///< Maximum number of Denali messages that can be pending ACK at any given time
 
 #define MAX_FPGA_CLOCK_SPEED_ERRORS     3       ///< maximum number of FPGA clock speed errors within window period before alarm
@@ -596,6 +596,7 @@
                     // If message from UI channel, mark UI communication so HD can begin transmitting
                     if ( ( COMM_BUFFER_IN_CAN_UI_2_HD == MSG_IN_BUFFERS[ i ] ) || ( COMM_BUFFER_IN_CAN_UI_BROADCAST == MSG_IN_BUFFERS[ i ] ) )
                     {
+                        timeOfLastUICheckIn = getMSTimerCount();
                         uiDidCommunicate = TRUE;
                     }
                 }
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r14d740bbb065f043daaa348bcda5f447e1c16a32 -r04717003bb672ca3ed507a924156e141db2d5855
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 14d740bbb065f043daaa348bcda5f447e1c16a32)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 04717003bb672ca3ed507a924156e141db2d5855)
@@ -2063,16 +2063,7 @@
  *************************************************************************/
 void handleUICheckIn( MESSAGE_T *message )
 {
-
-    if ( message->hdr.payloadLen == sizeof( U32 ) )
-    {
-        checkInFromUI();
-    }
-
-    else
-    {
-        sendAckResponseMsg( (MSG_ID_T)message->hdr.msgID, COMM_BUFFER_OUT_CAN_HD_2_UI, FALSE );
-    }
+    checkInFromUI();
 }
 
 /*********************************************************************//**