Thanks for the responses. Similar to Ed's suggestion, I'm planning on having some artificial branches protruding out from the dripwall which will offer drier spots for broms, orchids and other epiphytes that may not appreciated the constant water flow.
However, I'd like the dripwall to provide an entirely moss covered backdrop for these plants, hence my question. Based on your responses it sounds like clay may be the better option. Given the constant water flow and the potential nutrient load of the aquarium water I'm thinking emersed aquatic "moss" (eg. riccia, christimas moss and willow moss) will probably be better suited to this than true terrestrial moss. I know people have had luck growing this stuff under constant flow on epiweb-like materials. In this example a person sandwiched the moss between aquarium filter foam and plastic window screening under a filter outleft. The moss eventually grew through the screen quite nicely:
http://www.aquaticplantcentral.com/f...y-tank-18.html
Has anyone had any experience growing these aquatic moss species on clay dripwalls?
