Anyone know the best way to set up a filter for a pond?

Question:I'm new to all this, having inherited a pond with my new house. The filter continually gets clogged. The filter is basically a box with three pieces of square foam inside and some tube cuttings at the bottom. At the moment money is too tight to buy a new one, anyone know a method that will stop the sponge clogging and the water going in to the overspill and straight back to the pond? Help!

Answers:
It helps to keep a wire mesh over the top (depending on size of pond) to keep unwanted debris out of the water which will help the filter system also make sure the filter system is the correct size so it doesn't have to work so hard. I purchased all my pond equipment from Lowes & they seem very helpful on answer questions.. Good luck.