You should be able to find it at your lfs
. I have the same kind of filter and thats where I got one for mine. It will eventually wear down and need to be replaced. But it takes along time.
55 Gallon-two clown knifefish, chocolate pleco
46 Gallon Bow Front-Planted-swords, java fern and African cichlids, sail fin pleco
29 Gallon-black ghost knifefish, bristlenose pleco
10 gallon-brackish, figure-eight puffer, knight goby