Question on 12G Nano Cube DX??

[idle0095]

I got a free nano cube dx 12g on craigslist. It is missing all the filter media. I cant seem to find the answer at all but what goes in the 3 stage chambers? first one is were the water goes in, second is the middle chamber and the last is were the pump is.

What should i put in each chamber. I know the last chamber nothing because of the pump.

Thanks