I just put in an order for this, which I also think would show really well in a pico. It is slightly calcified, though, so you'd have to manage supplements--or water changes would do the trick.
I also ordered this:
String of pearls would look amazing in a pico and is very easy to prune. Definitely a winner.
I tried before at this one and failed due to a HUGE tank swing, but this looks nice, is a super slow grower and easy to prune:
Worth considering:
Blue hypnea -- slowish grower and looks great under the right light. In a pico might not get blown around too much. I could never keep it because my large snails would trample/dislodge it and send it right into the overflow.
Ones to avoid in a pico:
Gracilaria hayi -- too fast grower. Very bushy and looks nice but can bottom out nutrients and cause dinos (ask me how I know)
Any Caulerpa -- way too fast and invasive.
Botrycladia -- look very similar to string of pearls and looks great! Slow grower! Easy to prune! Wait, what's the problem then? Well, as it grows, the big bunch of grapes ends up very high in the water column--they're buoyant--and it shades a lot of what's below it, and in a pico, you don't have that much vertical space, so you end up with just a trunk and a bunch of grapes at the top of the tank. In this sense, String of Pearls is superior.
Halymenia -- aka dragon's breadth. It's a beautiful macro, but it looks best when it has a decent amount of space to fill in, which you don't have in a pico.
Stringy Gracilaria species -- I like them, and I just ordered some, but they can be a pain to keep down and look better when they have a lot of head space, which a pico doesn't have.
Hope that helps!!
