Well, let's see. Those were 6 inch high pots Soil level about 1 inch less than pot height, plants were about 2 to 4 inches high. So, I was running about an effective height of 7 to 10 inches above soil level or so throughout. I guess the main thing is to have it as close as reasonable without damaging the leaves. I raised mine once during the process when I saw some yellowing and browning on a couple of the taller leaf tips. I suppose in the beginning, one could start out a little on the high side and work down to that point and then move the height back up perodically as the plants grow. Kind of trial and error; main thing is watch for leaf damage. Keep in mind I was running two and three units also--but I think one would do just fine with a single unit at a lower height as Rick suggests.
