a while back, a friend told me that if I put moss in a blender with a little egg or soymilk, I could make a paint, that you could paint concrete with and it would grow moss outdoors... I'm wondering if this could apply to moss wall building in the tank, by making a paint, dipping a single layer of screen in the paint, and then starting the growth in an empty, but 100% humid tank... once the moss was 1/8" long, I'd imagine you could fill the tank... just a tought. sorry, I'm rambling.
nice wall!