I make some, buy some from Ebay, Have a LFS
that does still carry different brands of them ( Just goes to show the value of a Mom & Pop shop
) and got some from the Florida Fish Farmers Association' s retail site. ( FTFFA Co-Op Store, Aquaculture Supplier
)So there are many choices and many types ( Lee's, Hydro Sponge, Bio sponge, etc) that it shouldn't be too difficult to get them.