Ok so I've heard that a lot I people don't replace their filters unless the are falling apart because that's where most of your bb is. Also that the carbon is really there to help make your water not stink basically? ( not completely sure on all of this) but I was wondering how do I replace the carbon then? And if I really even need to? Also do you change your filter or leave it be? Also I've heard people talk about adding sponges to help their filtration can you add hem to any types of filter or are there filters made to hold them?