Backyard Aquaponics
A place to discuss aquaponics

I'm not familiar with what you're describing. I use coco because it's cheap and renewable. I buy the bags with chunks and then try to separate the larger pieces. I have a bag made from the blue screen stuff to catch loose pieces before the enter the sump.

The coco is light and shouldn't heat up GBs as much as clay pellets would. If you find a place working with coconuts they may give you the coir for free.

Another idea I had was to use the small red clay bricks broken into small pieces. You could probably collect them left over from building sites.

But I think if you're looking to go commercial, it would have to be foam rafts.