Whisper 5-15 Upgrade To Filter Media

[AML225]

I have a 5-15 Whisper power filter and I was wondering what I can do to improve the performance of the that filter? Specifically in terms of adding more carbon to remove discoloration. I red somewhere a quick DIY tutorial on this exact process, something like opening up the pouch and stuffing in bio-balls, etc.

How can I do this and still maintain my cycled bacteria?

thanks.