jhnrb is a smart man that gives good advice. Go light on additions and takeyour time. Bio systems take a long time to mature properly. Some tanks without adequate live rock and/or deep sand beds never obtain a fully mature bio system. They tend to have repetive problems with high nitrate levels, and spikes in ammonia and nitrites after additions of a large number of fish, coral or after accidents like dropping a full container of food in the tank and only being able to remove a small portion of it. A fully mature biologiacl system will take these occurances in stride without any noticeable water parameter changes, except ussually a lowering of dissolved oxygen for a while, and some lowering of pH. Bacteria go through massive amounts of oxygen when given massive amounts of food.