the tank is new.. but the water and rocks are fully cycled... I assume that is what we are calling it... I bought the rock out of an established tanks.. Cured rock... and the water was ready...... I got the stuff from all about fish.... it seems like this is a normal thing to sell the water from his display tanks.... I assume he has good water and the rocks .. I have been told that he only sells them if they are cured.... I tend to trust people until they do me wrong.... real nice guy.. I have no reason to question what he has told me.... he said these Zoas.. (if that is what they are) would survive in my tank...