if i was you i would leave the sponge and put some filter floss on top of the sponge. this will help polish the water and act as more mechanical filtration.
i would then remove the carbon, which really does nothing unless you are removing medication, and put in some sort of bio filtration. i use the bio media that comes with ac's, but if you dont like it add what you like.
i do what i put above and it has worked very well for me so far. make sure to rinse the sponge once in a while in tank water and i replace the filter floss every week or two. alot of people do alot of different things so im sure you will get some other good ideas.
i would then remove the carbon, which really does nothing unless you are removing medication, and put in some sort of bio filtration. i use the bio media that comes with ac's, but if you dont like it add what you like.
i do what i put above and it has worked very well for me so far. make sure to rinse the sponge once in a while in tank water and i replace the filter floss every week or two. alot of people do alot of different things so im sure you will get some other good ideas.