Symantec 5230 Appliance - Disk Space Warning Message

I am receiveing an email alert (Warning) each morning relating to disk space utilisation on the de-dup pool in my 5230 Appliance (which is at 80%) and wish to raise the threshold for the warning to 85%.  The appliance is sitting steady at 80% so I am not too concerned.  Where can I change the limit ?

Thanks,

AJ