This guy I have been watching for about 6 months now. Hes from a pet shop local to myself although I'v never been in. Hes working with moving bed filters, starting off with K1 media and now prefering these sort of sand and glass balls. These are very cheap to make and I'v been running one for about 4 months. In the description of his videos you can buy his media.
Heres a video on how to make his first moving bed filter design, with K1 media from a bottle;