I'm not familiar with an 'aqua filter' but it might help describing how I clean mine:
I do a water change every week, and every other week or so I clean the filter at the same time. Sometimes I will do it anyway if, for example, lots of plant bits are stuck in it.
Squeeze out the white wool/floss in old tank water, and replace it if there is too many bits stuck in it.
Squeeze each sponge in the old tank water, removing any bits stuck in it.
Vacuum inside, at the bottom of the filter every few weeks (a lot of muck collects down there).
If it looks like it needs it then I clean the powerhead by taking it apart and wiping the muck out.
I have never changed the actual sponges yet.
Here is a pic of my filter.
