Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -rc429cf7f50851acbaca6e800957ef44cc1fa2162 -re781d3b87509e75ae6a2bde6da3d5819b7b5a2da
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision c429cf7f50851acbaca6e800957ef44cc1fa2162)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision e781d3b87509e75ae6a2bde6da3d5819b7b5a2da)
@@ -974,25 +974,26 @@
         U32 lastFlushCompleteDate     = data.dgUsageInfo.lastBasicFlushCompleteDateEpoch;
         U32 lastStartTxTimeDate       = usageRecord.txLastStartTimeEpoch;
 
-        // Last Treatment Start > Last Heat Disinfect Complete AND Last Treatment Start > Last Chem Disinfect Complete
-        BOOL hasDisBeenDone = ( ( ( lastStartTxTimeDate > lastChemCompleteDate ) && ( lastStartTxTimeDate > lastHeatCompleteDate ) ) ? FALSE : TRUE );
+        // Last Treatment Start < Last Heat Disinfect Complete or Last Treatment Start < Last Chem Disinfect Complete so it means at least a heat disinfect
+        // or a chemical disinfect has been done since the last treatment
+        BOOL hasDisBeenDone = ( ( ( lastStartTxTimeDate < lastChemCompleteDate ) || ( lastStartTxTimeDate < lastHeatCompleteDate ) ) ? TRUE : FALSE );
 
-        // Last Chem Disinfect Complete < Current Time – Chem Disinfect Interval
+        // Last Chem Disinfect Complete < Current Time – Chem Disinfect Interval, so the chemical disinfect that has been done has not been expired
         BOOL isChemDisValid = ( lastChemCompleteDate < ( getRTCTimestamp() - DISINFECTS_TIME_INTERVAL_S ) ? TRUE : FALSE );
 
-        // Last Heat Disinfect Complete < Current Time – Heat Disinfect Interval
+        // Last Heat Disinfect Complete < Current Time – Heat Disinfect Interval, so the heat disinfect that has been done has not been expired
         BOOL isHeatDisValid = ( lastHeatCompleteDate < ( getRTCTimestamp() - DISINFECTS_TIME_INTERVAL_S ) ? TRUE : FALSE );
 
-        // Last Chem Flush Complete < Last Chem Disinfect Start
-        BOOL isChemFlushComplete = ( lastChemFlushCompleteDate < lastChemCompleteDate ? FALSE : TRUE );
+        // Last Chem Flush Complete < Last Chem Disinfect Start, so after running a chemical disinfect, a chemical disinfect flush has been done
+        BOOL isChemFlushComplete = ( lastChemFlushCompleteDate > lastChemCompleteDate ? TRUE : FALSE );
 
-        // Last Basic Flush Complete < Current Time – Flush Interval AND Last Heat Disinfect Complete < Current Time – Flush Interval
-        // AND Last Chem Flush Complete < Current Time – Flush Interval
-        BOOL isBasicFlushValid   = ( lastFlushCompleteDate     < ( getRTCTimestamp() - FLUSH_TIME_INTERVAL_S ) ? TRUE : FALSE );
-        BOOL isHeatDisFlushValid = ( lastHeatCompleteDate      < ( getRTCTimestamp() - FLUSH_TIME_INTERVAL_S ) ? TRUE : FALSE );
-        BOOL isChemFlushValid    = ( lastChemFlushCompleteDate < ( getRTCTimestamp() - FLUSH_TIME_INTERVAL_S ) ? TRUE : FALSE );
-        BOOL isFlushValid        = ( isBasicFlushValid | isHeatDisFlushValid | isChemFlushValid );
+        // If either of the basic flush, heat disinfect, or chemical disinfect flush have been done within the interval, it means the filters have been flushed
+        BOOL isBasicFlushValid   = ( lastFlushCompleteDate     < ( getRTCTimestamp() - FLUSH_TIME_INTERVAL_S ) ? TRUE : TRUE );
+        BOOL isHeatDisFlushValid = ( lastHeatCompleteDate      < ( getRTCTimestamp() - FLUSH_TIME_INTERVAL_S ) ? TRUE : TRUE );
+        BOOL isChemFlushValid    = ( lastChemFlushCompleteDate < ( getRTCTimestamp() - FLUSH_TIME_INTERVAL_S ) ? TRUE : TRUE );
+        BOOL isFlushValid        = ( isBasicFlushValid || isHeatDisFlushValid || isChemFlushValid );
 
+        // If all of the above conditions are true, it means we can start a treatment
         if ( ( TRUE == hasDisBeenDone ) && ( TRUE == isChemDisValid ) && ( TRUE == isHeatDisValid ) && ( TRUE == isChemFlushComplete ) && ( TRUE == isFlushValid ) )
         {
             status = TRUE;