Replace the carbon with Matrix or something way more benificial to your bio's. Carbon is expensive and disposable. Matrix, while expensive, has a surface area that will surpass the carbon and will last forever.
Place the Matrix in a media bag and simply drop it in your filter.
You dont have to use Matrix either. Go look for media typically used in canister filters and simply find one that suits your fancy. Eheim Ehfimech, Bio Balls, Bio Rings...whatever you want...just ditch the carbon.