You can take it out and add another sponge or ceramic bio rings to increase your biological filter capacity. That's what I did on my AquaClear and you don't have to waste your money on the constant replacement of carbon as it does wear out. You can use carbon to help with medication and tannin removal and to decrease smells in the tank if that's what you so desire to do. Some people claim that it makes the water clear but your water should be clear without carbon and shouldn't be smelly anyway.
Ciao