Create cron task to back up database
$ vim /etc/cron.d/db_backups
# m h dom mon dow user command
12 3 * * * <user> pg_dump -c <db_name> > \
"/path/to/backups/`date +\%Y-\%m-\%d-<db_name>.sql`"
This will create a backup at 3:12am every day. Be sure to put a newline at the end of the file.
Don't forget to create the /path/to/backups
directory and allow postgres to write to it.