Simply put, if what you are seeing in your tank is a green, feathery looking mass, it is probably green hair or net algae. Once this type of algae gets a foothold in a saltwater aquarium, it can soon cover everything in your tank if prompt measures are not taken. The solution for getting rid of this type of algae is the same as the prevention: Starve it into oblivion.
cited from: http://saltaquarium.about.com/cs/algaecontrol/f/blqagreenslime.htm
Just an FYI citing a saltwater treatment in a freshwater thread really does not help the original poster of the thread.