The growing media you can use instead of those expensive extruded clay balls or cat litter is buy a growing medium for bonsai plants found at a bonsai nursery. Perfect size for grow beds.
Also the plants I wanted to recommend is the watercress, my koi fish love to eat them and also excellent for human consumption. Watercress thrive on moving water or shallow water like water fall. Kangkong plants also is an excellent around the perimeter of the pond planted in a pot and let the stem float and grow to the pond water for the fish to eat. It’s also good for human consumption. You can find these plants at an Asian store.
Jay Smithy wrote:Even pea gravel, possibly even plain sand, therer are pro's and con's for everything, but in an intrinsically 'Natural' system such as Aquaponics, why buy expensive, trendy growing media when it is entirely unneccessary?!?
It does work with sand. My system was out of commission this summer, because the sand, grow bed and support structure I used weren't a good match. It improved each year, presumably because of organic matter accumulating. Finally the weight made it slump enough for water to run over before it gets to the drain. During the course of a day, it would drain the fish tank down to about 6". May have improved from better mineralization, too. I always buried a bit of organics in it, apple cores, corn cobs, a few sticks. The last summer that it ran, I mulched it with grass clippings. All organic matter, but grown in soil, so probably had more mineral diversity than my sand had.
IAVs seems to be either the first aquaponics, or the precursor to aquaponics. (So I'm told.) It uses sand. Here's a link to a discussion about it here on permies. That thread also has a picture or two of my system and a link to where I basically logged my progress on line for a year or three, if you're interested.
I had stuff actively growing in it, (had to water it with a hose) so I didn't tear it down. Now that everything's dormant, I hope to have it in shape to run again in the spring.
I can recommend pea gravel for a permanent location. It is really heavy. I know because I shoveled 13 tons of it. But as a substrate it wicks water ok and is a good root support. It is cheaper than many options, easily obtainable in bulk, and doesn't need replacing.