def __get_metrics(self):
        """ Each metric must have its own filters copy to modify it freely"""
        esfilters_closed = None
        esfilters_opened = None
        if self.esfilters:
            esfilters_closed = self.esfilters.copy()
            esfilters_opened = self.esfilters.copy()

        closed = self.closed_class(self.es_url, self.es_index,
                                   start=self.start, end=self.end,
                                   esfilters=esfilters_closed, interval=self.interval)
        opened = self.opened_class(self.es_url, self.es_index,
                                   start=self.start, end=self.end,
                                   esfilters=esfilters_opened, interval=self.interval)
        return (closed, opened)