Index: firmware/App/Modes/ModeTreatment.c
===================================================================
diff -u -rca238a4fc2400ffaf3c2a90c6e923a87b8dac4d2 -r672ea05607319696b238f1778190c86ab34e7abc
--- firmware/App/Modes/ModeTreatment.c	(.../ModeTreatment.c)	(revision ca238a4fc2400ffaf3c2a90c6e923a87b8dac4d2)
+++ firmware/App/Modes/ModeTreatment.c	(.../ModeTreatment.c)	(revision 672ea05607319696b238f1778190c86ab34e7abc)
@@ -1142,19 +1142,8 @@
         {
             pendingUFRateChange = 0.0;
         }
-        // Verify treatment duration change would be valid (leave zero if not valid - UI will disable option)
-        if ( ( trtTime <= MAX_TREATMENT_TIME_MINUTES ) && ( trtTime >= getMinTreatmentTimeInMinutes() ) &&
-             ( dialVolume <= MAX_DIALYSATE_VOLUME_ML ) )
-        {
-            result = TRUE;
-            pendingUFVolumeChange = uFVolume;
-            pendingTreatmentTimeChange = trtTime;
-            timeDiff = trtTime - ( (U32)( (F32)presTreatmentTimeSecs / (F32)SEC_PER_MIN ) + 1 );
-        }
-        else
-        {
-            pendingTreatmentTimeChange = 0;
-        }
+        // Treatment duration change is now never valid - leave zero - UI will disable option)
+        pendingTreatmentTimeChange = 0;
         // If neither option works, reject for UF rate
         if ( FALSE == result )
         {
@@ -1216,14 +1205,9 @@
         presMaxUFVolumeML = pendingUFVolumeChange;
         setTreatmentParameterF32( TREATMENT_PARAM_UF_VOLUME, ( presMaxUFVolumeML / (F32)ML_PER_LITER ) );
 
-        // Which setting does user want to adjust to accommodate the UF volume change? (treatment time or UF rate)
-        if ( UF_ADJ_TREATMENT_TIME == adjustment )
+        // User should only allow UF rate adjustment to achieve UF volume change
+        if ( UF_ADJ_UF_RATE == adjustment )
         {
-            presTreatmentTimeSecs = pendingTreatmentTimeChange * SEC_PER_MIN;
-            setTreatmentParameterU32( TREATMENT_PARAM_TREATMENT_DURATION, ( presTreatmentTimeSecs / SEC_PER_MIN ) );
-        }
-        else // Must be adjusting UF rate then
-        {
             sendTreatmentLogEventData( UF_RATE_CHANGE_EVENT, presUFRate, pendingUFRateChange );
             presUFRate = pendingUFRateChange;
             signalInitiatePressureStabilization();