[Delphinus]

I would recommend against even trying. Unless you are very knowledgeable about the various seaweed species along the coasts and their various tolerances (there are some good books on the topic, I looked into this myself when I first got into the hobby) or unless if you are trying a coldwater tank. The problem is a lot of them can release enough toxins to kill everything if for example they get too warm. A few years back I found a really good book on the subject, I'll see if I can find it and post the title, it makes for an interesting read particularly if you're into finding out "what is this whatzit" that you can find on shoreline walks..