If you live near a flowing body of water you should be able to find some silt to mix with the EC, which would give you usable nutrients and, if the silt is largely clay, some CEC too. I'm not recommending that you do that, but it is a way to try something new that Tom's research suggests might work well. Just be sure to cap it with an inch or so of EC, or mix less silt with the EC and vacuum up the silt from the top. I'm still very pleased with my experimental substrate.