most moss balls you can buy are not moss they are a form of domesticated algea. some say they do not release algea into your tank and some say they can introduce algae if you are looking for moss to cover hardscape then find someone or somewhere that just sells moss (flame moss, taiwan moss, java moss, Xmas moss, fissiden or somthing along those lines) then tie it to your hardscape and they will attach to it in no time.