diff --git a/da/ct/obs.py b/da/ct/obs.py
index fe5fc3e250c6648b244b0cdee35b5b53b0b21968..de64614754cf2dbec665b55c1e99195ec969a015 100755
--- a/da/ct/obs.py
+++ b/da/ct/obs.py
@@ -142,7 +142,7 @@ class CtObservations(Observation):
                 
                 index = obs_ids.index(id)
                 #print id,val,val.shape
-                dummy = self.Data[index].simulated = val*1e6  # to umol/mol
+                dummy = self.Data[index].simulated = val  # in mol/mol
 
             else:     
 
@@ -436,8 +436,8 @@ class CtObservations(Observation):
         savedict['dtype']       = "char"
         savedict['dims']        = dimid+dim200char
         savedict['values']      = data
-        savedict['missing_value'] = '-'
-        savedict['_FillValue']    = '-'
+        savedict['missing_value'] = '!'
+        savedict['_FillValue']    = '!'
         dummy                   = f.AddData(savedict)
 
         status       = f.close()