I started a saltwater tank when we went to the beach for a week. For plants, I used 4 kinds of seaweed that washed up in the tide. For a week and a half it was wonderful. Then I noticed that one of the kinds of seaweed is dieing and rotting at the tips and water is being pickled a brownish color. The animals in there are doing fine. I'm not too worried about the tank because it was virtually no cost. But I would like to keep things alive if I can. Maybe there are certain kinds of seaweed that don't do well in tanks. Does anyone have experience with these issues?