My earliest understanding of mechanical filtration was based on adsorption. Eheim sold 2 versions of it. Both were extruded, smooth, non-reactive plastic. It looked like string. The coarser of the 2, the green stuff was first in the filter. The second was the white version because it would reduce the size of the advancing material even further. Next, I used a bag of chemipure carbon, then filter floss. ALL smashed into a Eheim cannister.
Of course things don't work well this way, but it seemed fine at the time. I got this "knowledge" from the Old Town Aquarium in northern Chicago.