Don't use config backend type if it's not set
diff --git a/planetstack/core/models/site.py b/planetstack/core/models/site.py
index af57ed2..33d9437 100644
--- a/planetstack/core/models/site.py
+++ b/planetstack/core/models/site.py
@@ -20,7 +20,7 @@
 
         parent_queryset = parent.get_queryset() if hasattr(parent, "get_queryset") else parent.get_query_set()
         if (backend_type):
-            return parent_queryset.filter(Q(deployment__backend_type=config.observer_backend_type)|Q(backend_type=None))
+            return parent_queryset.filter(Q(deployment__backend_type=backend_type)|Q(backend_type=None))
         else:
             return parent_queryset
 
@@ -41,7 +41,7 @@
         parent_queryset = parent.get_queryset() if hasattr(parent, "get_queryset") else parent.get_query_set()
 
         if backend_type:
-            return parent_queryset.filter(Q(backend_type=config.observer_backend_type)|Q(backend_type=None))
+            return parent_queryset.filter(Q(backend_type=backend_type)|Q(backend_type=None))
         else:
             return parent_queryset
 
@@ -61,7 +61,7 @@
         parent_queryset = parent.get_queryset() if hasattr(parent, "get_queryset") else parent.get_query_set()
 
         if backend_type:
-            return parent_queryset.filter(Q(deployment__backend_type=config.observer_backend_type)|Q(backend_type=None))
+            return parent_queryset.filter(Q(deployment__backend_type=backend_type)|Q(backend_type=None))
         else:
             return parent_queryset
 
@@ -82,9 +82,9 @@
         parent_queryset = parent.get_queryset() if hasattr(parent, "get_queryset") else parent.get_query_set()
 
         if backend_type:
-            return parent_queryset.filter(Q(backend_type=config.observer_backend_type)|Q(backend_type=None))
+            return parent_queryset.filter(Q(backend_type=backend_type)|Q(backend_type=None))
         else:
-            return parent_queryset.filter(Q(backend_type=config.observer_backend_type)|Q(backend_type=None))
+            return parent_queryset.filter(Q(backend_type=backend_type)|Q(backend_type=None))
 
     # deprecated in django 1.7 in favor of get_queryset().
     def get_query_set(self):