I just cut the cartridges down to the plastic side. I just use it as a barrier for the media and fill the rest of the filter behind it with filter floss and bio mediadjdlemma;2223846; said:So, I run carbon in my tanks (penguin 200's), how do you replace the carbon with something else? Do you use an old carbon pad, take out the carbon from the plastic, then what? Attach pot scrubbies or something? I would love to not have to not buy carbon anymore......