diff --git a/accountant/models/accounts.py b/accountant/models/accounts.py
index 27d7647..d5924d5 100644
--- a/accountant/models/accounts.py
+++ b/accountant/models/accounts.py
@@ -124,6 +124,84 @@ class Account(db.Model):
 
         return query
 
+    def daily_balances(self, begin=None, end=None):
+        """Return a query for daily balances with expenses, revenues, income
+        and balance per day for this account and an optional specifir range."""
+
+        #end = end if end else arrow.now().ceil('month').date()
+
+        query = db.session.query(
+            Operation.operation_date,
+            db.func.coalesce(
+                db.func.sum(
+                    Operation.value
+                ).filter(
+                    db.func.sign(Operation.value) == -1
+                ).over(
+                    partition_by=[
+                        Operation.account_id,
+                        Operation.operation_date
+                    ],
+                ),
+                0
+            ).label("expenses"),
+            db.func.coalesce(
+                db.func.sum(
+                    Operation.value
+                ).filter(
+                    db.func.sign(Operation.value) == 1
+                ).over(
+                    partition_by=[
+                        Operation.account_id,
+                        Operation.operation_date
+                    ],
+                ),
+                0
+            ).label("revenues"),
+            db.func.coalesce(
+                db.func.sum(
+                    Operation.value
+                ).over(
+                    partition_by=[
+                        Operation.account_id,
+                        Operation.operation_date
+                    ],
+                )
+            ).label("income"),
+            db.func.coalesce(
+                db.func.sum(
+                    Operation.value
+                ).over(
+                    partition_by=Operation.account_id,
+                    order_by=Operation.operation_date
+                )
+            ).label("balance")
+        ).distinct(
+        ).order_by(
+            Operation.operation_date
+        ).filter(
+            Operation.account_id == self.id
+        )
+
+        if begin:
+            base_query = query.subquery()
+
+            query = db.session.query(
+                base_query
+            ).filter(
+                base_query.c.operation_date >= str(begin)
+            ).order_by(
+                base_query.c.operation_date
+            )
+
+            if end:
+                query = query.filter(query.c.operation_date <= str(end))
+
+        elif end:
+            query = query.filter(Operation.operation_date <= str(end))
+
+        return query
+
     @db.validates('authorized_overdraft')
     def validate_authorized_overdraft(self, key, authorized_overdraft):
         """Validator for authorized_overdraft : must be negative."""
diff --git a/accountant/models/operations.py b/accountant/models/operations.py
index ae8ff06..fb90f46 100644
--- a/accountant/models/operations.py
+++ b/accountant/models/operations.py
@@ -132,77 +132,3 @@ class Operation(db.Model):
         )
 
         return query
-
-    @classmethod
-    def query_daily_balances(cls, account, begin=None, end=None):
-        """Get expenses, revenues, income and balance per day for a specific
-        range and a specific account."""
-        if isinstance(account, (int, str)):
-            account_id = account
-        else:
-            account_id = account.id
-
-        end = end if end else arrow.now().ceil('month').date()
-
-        query = db.session.query(
-            cls.operation_date,
-            db.func.coalesce(
-                db.func.sum(
-                    cls.value
-                ).filter(
-                    db.func.sign(cls.value) == -1
-                ).over(
-                    partition_by=[cls.account_id, cls.operation_date],
-                ),
-                0
-            ).label("expenses"),
-            db.func.coalesce(
-                db.func.sum(
-                    cls.value
-                ).filter(
-                    db.func.sign(cls.value) == 1
-                ).over(
-                    partition_by=[cls.account_id, cls.operation_date],
-                ),
-                0
-            ).label("revenues"),
-            db.func.coalesce(
-                db.func.sum(
-                    cls.value
-                ).over(
-                    partition_by=[cls.account_id, cls.operation_date],
-                )
-            ).label("income"),
-            db.func.coalesce(
-                db.func.sum(
-                    cls.value
-                ).over(
-                    partition_by=cls.account_id,
-                    order_by=cls.operation_date
-                )
-            ).label("balance")
-        ).distinct(
-        ).order_by(
-            cls.operation_date
-        ).filter(
-            cls.account_id == account_id
-        )
-
-        if begin:
-            base_query = query.subquery()
-
-            query = db.session.query(
-                base_query
-            ).filter(
-                base_query.c.operation_date >= str(begin)
-            ).order_by(
-                base_query.c.operation_date
-            )
-
-            if end:
-                query = query.filter(query.c.operation_date <= str(end))
-
-        elif end:
-            query = query.filter(cls.operation_date <= str(end))
-
-        return query
diff --git a/accountant/views/accounts.py b/accountant/views/accounts.py
index f769c7d..5cc89d4 100644
--- a/accountant/views/accounts.py
+++ b/accountant/views/accounts.py
@@ -9,7 +9,6 @@ from flask_restplus import Namespace, Resource, fields
 
 from ..models import db, row_as_dict, result_as_dicts
 from ..models.accounts import Account
-from ..models.operations import Operation
 
 
 # pylint: disable=invalid-name
@@ -361,6 +360,11 @@ class DailyBalancesResource(Resource):
 
         data = range_parser.parse_args()
 
+        account = Account.query().get(account_id)
+
+        if not account:
+            ns.abort(404, 'Account with id %d not found.' % account_id)
+
         return list(result_as_dicts(
-            Operation.query_daily_balances(account_id, **data)
+            account.daily_balances(account_id, **data)
         )), 200