Whisper filter

If you have a Whisper 30-60 like mine I'd only clean the bag. The sponge is holding beneficial bacteria so I'd only rinse it in aquarium water and only if has debris on it. That sponge is your bio filter.

Q
 
I clean it all in tank water.
 
Depending on your stock, and frequencies of pwc, I'd just keep an eye and when filters and sponges appear ready to change, just do it. Just don't do all at one time, and as RBishop recomments, swish them around in tank water.
 
AquariaCentral.com