When a new aquarium system is created, these bacterial colonies are not immediately present. They will be introduced into your system when your liverock is added and will grow within the porous rock. The process that triggers the cycle into starting is kind of like a reverse process. There will be denitrifying bacteria present on the rock that you add, but there will be no waste available to feed them. As the bacteria and other life dies off on the rock, ammonia will be created. This new ammonia feeds the remaining bacteria, which will then start the cycle process. Other methods may be used to start the process sooner, such as adding a small piece of uncooked shrimp, that will decay into ammonia.
The amount of time that the cycle is going to take in a new system is difficult to predict. On average, it can take anywhere from two weeks to a month. If the rock is 'uncured', it may take longer for the existing die off to decay. If the rock is 'pre-cured' or 'cured', then the cycle process should complete quicker. More information on these liverock choices can be found here.
So what should you do during the cycle? Keep your lights running on their regular 10-12 hour schedule. Do not cycle your tank with the lights off, unless you want the life on the live rock to die off. Do not perform any partial water changes during the the process, as doing so will stall the cycle from completing. Some people have experimented with doing very small water changes during the cycle to keep the ammonia levels from getting extremely high. The thought behind this method is that it will help preserve the life that came on your live rock. The benefits, if any, are not well known at this time however.
By Christopher Marks •Cycling Your Tank