From FrugalReef

New Tank Syndrome is what happens when a new tank is established and stocked before the necessary bacterial colonies have developed. That is, the tank is established and stocked without first allowing it to cycle. This condition can also come back if medication is used that destroy the bacteria colonies, or the substrate is replaced, among other things.

New Tank Syndrome is characterized by high levels of Ammonia and Nitrate. It usually takes about 30 days after the first specimen is added for a tank to completely cycle. Water changes will dilute the ammonia and nitrite concentrations but not stop them from building up again.

If you already have valuable specimens in your tank because you've stocked it too fast, your best bet is to remove some of them if you can. If not, adding live rock will help significantly speed up the cycling time. Adding a live bacteria culture can also help, but be advised that not all these products work.

[edit] See Also

• Nitrogen Cycle
• Cycling