Filter material for filtration system

[Spencer 411]

I am looking for a decent source for that green filter material you see on all the professional wash out filtration systems. From what I have found so far it is basically the same as a pond filter. I think it might be called “matala”, but im not sure if that is the right stuff. Can anyone chime in on what this stuff is called and a good source to find larger pieces/sheets that can be cut to size? I can only find small pieces of this stuff.

Any help is appreciated!