Red garnet sand

[duanes]

https://hosting.photobucket.com/albums/i97/dstuer/substrate/.highres/034_zps16336c48.jpg

Found the above, at Garnett Abrassives Milwaukee, about 5 years ago it was $5 for 50 lbs.

https://hosting.photobucket.com/albums/i97/dstuer/substrate/.highres/006_zps72b4b8ae.jpg

I use lots of flow because my fish are mostly rheophillic, never had a problem with it blowing around.