Instructions
So, as long as your water quality is good enough, it's time to add corals! You can simply buy a water test kit or even bring in a sample to your LFS.
Soft corals are the easiest to raise. Among them, the easiest, and the prettiest in my opinion, are xenias. There are also posing xenias, which open and close....very cool. They grow very well in a healthy tank.
So, you add some posing xenias, and they stop posing. First thing is to give them time. They need to adapt to your tank. If still no posing, then there are a few possible problems. Water may not be clean enough - more water changes! Or there may not be enough light for them. Either add more light or move the xenias higher up in the tank. Or there is no food for them (yes, they do eat - filter feeders). You can get a bottle of coral "food" from your LFS. Most likely, however, is that you need to do more water changes first.
If the xenias do great, you may want to add an anemone. The reason I would add one so early is because the MOVE AROUND. Your other corals won't walk around the tank, and anemone will literally walk all over your other corals. So add it early if you want somewhere for your clownfish to live. Otherwise, I would suggest against an anemone, as they are pretty temperamental and can be time consuming (especially when they MOVE!).
So to add other corals, you can visit your local LFS. Buying online may be risky, and you won't get very big corals. Alternatively, you can find out where some other local tropical fish enthusiasts are and have a "frag" party. Basically, everyone brings a little part of their corals to trade/buy/sell.
How to Raise Coral in Your Tropical Aquarium
Ready to add some more exotic live to your tank? You will officially have a reef tank now that you are adding corals!