Be careful with the second one. Can't remember the name on top of my head, but I've had it before. Its a very slow grower, but once it starts growing it is almost impossible to remove from the rock. It clings to the rock extremely strongly. I've taken a wire brush to it and it grew back... If you don't mind the aquarium eventually being covered in it though, it does create a fantastic breeding zone for pods with how stiff it is, fish have a hard time getting to them unless they come to the top of the algae.