The flow path of the FX5 in the center baskets is from bottom to top so your pre-filter media needs to be in the bottom and the bio-media in the top...not the other way around.
The pre-filter media is designed to keep fine particles out of the bio-media to make it more efficiant however in the FX5 ...the outer foam rings do a great job of this on thier own and the additional pre-filter media becomes nothing more than additional, less efficiant bio-media.
This is why most long time users of FX5's do away with anything in the center baskets other than dedicated Bio-media.
The pre-filter media is designed to keep fine particles out of the bio-media to make it more efficiant however in the FX5 ...the outer foam rings do a great job of this on thier own and the additional pre-filter media becomes nothing more than additional, less efficiant bio-media.
This is why most long time users of FX5's do away with anything in the center baskets other than dedicated Bio-media.
What Wolf3101 states is correct. I have my fx5 setup like above and is working great for me. Adding more foam filters will just make it clog up more. 
But it is fixed now. Thank goodness I didn't lose any fish. Thanks to this thread I will be saving $$$, which will make my husband (not a fish person) a very happy man. 