Corals are basically divided into two different types, one is soft coral and another is hard coral. What differentiates between those two lies mainly on how they were formed in the first place. Soft coral came about when tiny larvae attach itself onto hard surfaces like a rock and then develops itself from there to become a polyp and then forms a colony. Hard corals on the other hand, construct its own outer skeleton (partly relies on symbiotic relationship with algae) by secreting limestone obtained from extract of calcium and carbonate from seawater that eventually covers around it.
Depending on which type of corals you are thinking to setup, there are different techniques and considerations you have to put in place. Coral are very delicate and sometimes finding suitable location for it to establish itself is very tricky. Some require heavy water movements while others need only moderate flow. Spacing is also another factor because corals do show aggression towards one another, as this is part of their natural instinct in the open environment. Most common type of aggression is stinging tentacles and therefore it is very important that you wear special type of protective glove when handing this particular corals during your marine tank setup. Corals survival in reef tank also depends on the type of fish that you intend to add. For example, certain angelfish family like the centropyge can cause massive destruction, thus either you make the right choice to pick the right fish or separate them to another aquarium.
Tank lighting is perhaps what determines the success and growth of the colony. Basically between fluorescent and metal halide, usually the latter comes as a preferred option since it produces higher intensity. However, bear in mind that not all corals actually prefer the same condition as there are some that become too sensitive with high intensity lighting that it even causes a burn and lead to its demise. During the acclimatization process, make sure that you observe the development and coloration so that you will know that you have provided enough. Too low intensity is not desirable as well because the coral will not be able to achieve maximum growth.
At this point of discussion after knowing the basic knowledge pertaining to the requirements, I would still suggest that if you intend to setup a marine coral tank, you should always get the experts' advice and help. The aquarium stores owner that sold it to you should provide after sales support. First thing first, check out how long the corals have remained in the saltwater aquarium after being harvested from sea. I would avoid purchasing those newly acquired direct from sea because the acclimatization process is very difficult and most of the time ended up losing the coral. The best option is to buy from coral farms as it is more eco-friendly thing to do.
Reef Tank Topics: Types of Live Rocks for Aquarium