Generally, it takes 4-6 weeks for a tank to cycle (and then it will cycle again everytime you add a fish, and if you add too many your tank will crash). If you are new to keeping fish in general, I would not recommend getting coral. I know, they are totally awesome creatures, but they require a lot of specific care. I do wonder though, what kind of coral were you thinking of adding? As well as what type of fish?

Also, see the link below on an article on cycling.
Cycling

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Phishie
Site Coordinator

"An ounce of prevention is worth a pound of cure."