Biohome is sintered glass, i missed? That somwhere before and have something else, but the same.. Tho not in a smooth saugage..
A lfs i come, sells this stuff as a pond filter medium in nameless bags rather cheap, i have it also in my sump and the helophyte filter in the garden pond. It definitely is frit.
After some research i found the manufacturer Unigeni Minerals and the stuff is called Unigrog.
I have the Unigrog 10
Both filters run like a charm on it, plants grow very well on it.. I have no idea what you guys pay for Biohome but this stuff is darn cheap and same stuff.
They have a rather wide range of granular filtermedia for water treatment. No idea about if their products go international, no international website.
Also used in other industries called Frit e.g. laboratories.. (we call it commonly Glassfoam) And because it is used in different applications it comes in these industries in standarized porosity and sizes.. Then you know what you are ordering or filtering with if you like it like that.