Fluval C3 questions

[Anna94]

I just finished setting up my new Fluval C3 and so far loving it, but I have two questions about it. 1. Do I really need the white cloth thing that sits on top of the biomedia box, and 2. Does the sponge/poly pad have to be replaced, if so how often, or can I just rinse it in tank water?

 

[UntimelyLord]

You don't need the cloth that goes on top of the biomedia box but it can help keep gunk out of the biomedia so you don't have to rinse the biomedia; if the cloth gets clogged you can rinse that in tank water.
Just rinse the sponge in tank water, I have the C4 and have only had to replace the sponge once after 4-5 years because the poly-pad side was falling apart. Then I let the new sponge run with the old sponge (a tight squeeze but it fit) for a couple weeks before removing the old one.