I have a 40g that I am going to convert to saltwater and I know how to make the DIY rock and how to cure it.After I cure it do I just put it in a saltwater tank with nothing in it and it will start growing coralline algae and stuff or do I need to add coralline algae and then it will spread? Can I just put a piece of porous concrete chunk from outside and it will start growing stuff on it without anything added? I am confused if it will grow on its own or if I need to buy stuff because I had a salt tank sit for a long time before with rocks in it and they did not grow stuff on them.