Sorry I missed this post. Creating the proper types and amounts of bacteria is one purpose of the cycle, yes. I have never heard of "fresh" live rock and/or live sand having enough bacteria in it to sustain life right away. There is no such thing as an instant tank even when using rock and such from a mature system. Bacteria also needs to build on your glass, equipment and everything else in the tank. In order to have this happen, you need to add something to the tank that will cause an ammonia spike which will start the cycle and the biological process continues from there until you have enough bacteria in the tank to support that ammonia producing organism, be it the bacteria that dies during transport of the live rock that you've added to your tank, addition of a raw shrimp or a fish. Once the bigger, initial cycle is over, you would then add another animal. As a result, more bacteria will grow to support the additional bioload...and so on and so on