I wanted to clean up my sump tank, and lower the Nitrates and Phosphates in my system. I kept having to wipe down the walls of my sump tank, clean up nasty detritus from the floor and wanted to keep it clean. I did some research on filter socks and the material used to make them. I went to Jo Ann fabrics and picked up 2 yards of white polyester felt, with some larger needles, and black thread. It took a bit to get my stitching consistent(not to mention made fun of :-D), but i was making about 2 socks a day while at work. I wanted the diameter to be 4" and had left over plastic tubing from my ATO DIY project, measured out 8" and stitched the top of the fabric loosely around that and so on. I made about 10 socks and just ran a load threw the washer on a short cycle on hot with no detergent, and then air dry them. I did notice a difference in the water clarity instantly after installing the socks. I bought a 3', 4" PVC tube from Menards and mimicked a guy's filter sock holder. I just took my recip saw and when to town, sandpapered the edges and it fits perfect in my sump. For about 10 bucks it worth spending a little time and have 10+ socks and holder.