jchase79, here is one link that I found helpful in my learning about EI, but I did other reading too: http://www.aquaticplantcentral.com/f...ing-guide.html
du3ce, thank you for your comment. My substrate is about 2 1/2 inches deep. From what I read, it seemed like a good depth, but I could be wrong. I haven't done much study on it. I agree it does look rather deep. However, isn't it good for the plants to have plenty of rooting space?