Okay so I came across an article about this company, Total Habitat, and their natural swimming pools. http://http://www.totalhabitat.com/natural-swimming-poolponds-nsps.html Really really awesome things going on there. I want one So bad. So reading into their methods some you come upon the term expanded shale. It's what they use/recomend as a media and as plant base. Its cheap, used in hydroponics and would seem to be an ideal media for aquariums and ponds. Especially for those DIY types like myself. I'm very much so thinking of trying it in my goldfish pond and maybe in a 10 gal in the house. Just to see how well it works and holds up. Anyone heard of it or tried it before?