I think I am going to go with 40 lbs, or two bags, since I would like to do a little sloping action, and maybe that will give me enough to make a nice landscape. If 40 is too much, I'll just share it with a friend of mine who is also considering getting Eco-Complete. But I want to do the sloping thing, so hopefully this will be just enough.
I'll also go with the root tabs or similar fertilizer to condition the bed. I am going to attempt the glosso experiment using a 55 watt compact fluorescent in my 20 long. I hope that will be enough.