I used the insides of the rolls of receipt paper that runs through cash registers at the local grocery stores. the cores are a light plastic with the "kaldness-like" veins. I cut them up, (tired fingers and a straight razor blade) and they seemed to work alright, but I was skeptical of the actual effectiveness of mine. I would like to test this moving media bed filter on a new tank to see how fast it can bring down the harmful levels of a new tank.
extremely well i use them in fbf's all the time and they work as well or better than K1 in all of my sumps, they are lighter so they are easier to fluidize in the sump.
I use basic aragonite sand. It dissolves slowly to help buffer alkalinity and pH, while providing bacterial media. Tends to gray the water for a day or 2 when first added.
My DIY FB is about 4ft tall X 8", so it uses about 5 lbs of sand. It was pressurized at first, but I found it hard to do maintenance on, and removed to top, and it works just as well.