Index: firmware/App/Modes/Dialysis.c
===================================================================
diff -u -rce3e0696642099164fa482c864509c67ce65579b -r6a414654391c1729525d55812abbf111ddef7d6a
--- firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision ce3e0696642099164fa482c864509c67ce65579b)
+++ firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 6a414654391c1729525d55812abbf111ddef7d6a)
@@ -1062,16 +1062,8 @@
  *************************************************************************/
 static void checkUFAccuracyAndVolume( void )
 {
-    F32 uFMeasRate = measUFVolume - lastUFVolumeChecked;
+    F32 uFMeasRate = measUFVolume - lastUFVolumeChecked;  // volumes are at start/end of 1 hour period, so implied rate is per hour
 
-    // check max UF rate in last hour   // TODO - is this check necessary considering next check below is a tighter check on this?
-//    if ( uFMeasRate > MAX_UF_RATE_ML_PER_HOUR )
-//    {
-//#ifndef DISABLE_UF_ALARMS
-//        SET_ALARM_WITH_1_F32_DATA( ALARM_ID_UF_RATE_TOO_HIGH_ERROR, uFMeasRate );
-//#endif
-//    }
-
     // check UF rate diff from target in last hour
     if ( uFMeasRate > maxUFRateAccuracyError_Ml_hr )
     {
Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -rac05209d7b6c65b22359754eced5ad2672d3092a -r6a414654391c1729525d55812abbf111ddef7d6a
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision ac05209d7b6c65b22359754eced5ad2672d3092a)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 6a414654391c1729525d55812abbf111ddef7d6a)
@@ -888,7 +888,7 @@
             if ( message.crc == crc8( (U08*)(&message), sizeof(MESSAGE_HEADER_T) + message.msg.hdr.payloadLen ) )
             {
                 // if ACK, mark pending message ACK'd
-                if ( MSG_ID_ACK == message.msg.hdr.msgID )
+                if ( MSG_ID_ACK_MESSAGE_THAT_REQUIRES_ACK == message.msg.hdr.msgID )
                 {
                     matchACKtoPendingACKList( message.msg.hdr.seqNo );
                 }
Index: firmware/App/Services/SystemComm.h
===================================================================
diff -u -rd91a24c730aeb5cd7e3eba9ef4eca78e442911f8 -r6a414654391c1729525d55812abbf111ddef7d6a
--- firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision d91a24c730aeb5cd7e3eba9ef4eca78e442911f8)
+++ firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision 6a414654391c1729525d55812abbf111ddef7d6a)
@@ -39,7 +39,6 @@
     #define PC_MESSAGE_PACKET_SIZE  8
 #endif
 
-#define MSG_ID_ACK                  0xFFFF                                                          ///< Denali message ID for acknowledging received messages (when required).
 #define MSG_ACK_BIT                 0x8000                                                          ///< ACK bit in sequence number that indicates an ACK is required.
 #define MAX_MSG_SEQ_NO              0x7FFF                                                          ///< Maximum sequence number for Denali message (then wraps to 1).
 #define MIN_MSG_SEQ_NO              0x0001                                                          ///< Minimum sequence number for Denali message.
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r395b6a6a9df782ebf1d331c43dc2d26a3fa59a03 -r6a414654391c1729525d55812abbf111ddef7d6a
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 395b6a6a9df782ebf1d331c43dc2d26a3fa59a03)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 6a414654391c1729525d55812abbf111ddef7d6a)
@@ -90,7 +90,7 @@
     data[ msgSize++ ] = MESSAGE_SYNC_BYTE;
 
     // set sequence # and ACK bit (unless this is an ACK to a received message)
-    if ( msg.hdr.msgID != MSG_ID_ACK )
+    if ( msg.hdr.msgID != MSG_ID_ACK_MESSAGE_THAT_REQUIRES_ACK )
     {
         // thread protect next sequence # access & increment
         _disable_IRQ();
@@ -165,7 +165,7 @@
     // send ACK back with same seq. #, but w/o ACK bit
     msg.hdr.seqNo = message->hdr.seqNo * -1;
     // ACK messages always have this ID
-    msg.hdr.msgID = MSG_ID_ACK;
+    msg.hdr.msgID = MSG_ID_ACK_MESSAGE_THAT_REQUIRES_ACK;
     // ACK messages always have no payload
     msg.hdr.payloadLen = 0;