Do some research on dosing systems, like calcium reactors, and kalk wasser. If you are very consistant with working on your tank you can dose calcium and kalk yourself with a simple drip system, if not there are dosing systems that can do that for you. When looking for coral find out what they eat because they do, some only need phyto, some like meety food like oyster eggs. Some coral also need iodine so decide what one coral you want is, and research just the one so you know what the requirements are before you invest in it. A good place to start are mushrooms and star pollups. Take your time and keep asking the good questions.