Ok so i live in tenneessee west tn to be exact. And i was wondering if anybody ever used clay soil from outside. Because there is plenty of clay soil here and i know it has to be rich in iron cause its got gray colors mixed in and its hard as a rock when not wet, but it gets soft when wet. I already have some in my ten gallon tank and my hairgrass seemsto lovethe clay soil. So i was wondering if this would be good for other plants to?