If you have filter media in the pipe or tank before the filter, it means that water is probably running backwards at some point in time. Is there any air charged storage tank after the iron filter? Is there a softener after the iron filter and if so any possibility that air is getting into it? Is there an outside hose bib before the iron filter that can drop the pressure below what is on the other side of the filter.
What clues do you have to support having to backwash your iron filter every two days? Maybe you have air building up in it and essentially you need to purge the air that often.