Before going any further, the question of course is: "does live sand need to be cycled" or to be more complete, "does live sand actually go through a cycle of its own"?
In most cases hobbyists who order live sand, receive the sand after an overnight or a two day shipping method. Some buy it from local pet shops (LPS) but those hobbyists appear to be in the minority. Most seem to order it from companies that need to ship it to them.
What happens to the so-called live sand during the time the sand travels, is hard to describe. Many variables are involved and a lot depends on how "live" the sand actually was to begin with.
Even if it was live (and I will define that later), one most important factor is how much organic material was actually present in the sand that was shipped.
This organic material can be looked at in at least two ways:
Live sand contains organic matter of different kinds. The most obvious form of organic material is the bacterial life forms that result in us calling the sand "live" to begin with.
That is, in fact, also the easiest definition of live sand.
Besides that though, the sand may contain dead organic material in the form of algal, bacterial or general animal life forms. This organic material may already be in various stages of decomposition, or may not.
I personally think that this is often overlooked by hobbyists who think that the sand is clean and does not contain detritus at all of any kind. Nothing is further from the truth. Live sand contains detritus and most of it is of organic nature.
During transportation additional life forms may, and will more than likely, die off, increasing the amount of dead organic material present in the sand hobbyists receive.
All this organic material decomposes in the tank and may give rise to small amounts of ammonia and the ensuing nitrite, as time goes by and the decay of this organic matrial continues.
This is, in reality, similar to what happens when anything dies in the aquarium and starts to decay, and in the process gives rise to ammonia which then, due to bacterial action, results in the appearance of nitrite and eventually nitrate.
Most of us do not think of it that way, but die off and decomposition do occur. If we already have live rock in the tank and if that live rock is already cycled, the appearance of this ammonia may well go unnoticed and not cause any problems.
If, on the other hand, the rock we have is not cycled, the decomposition that takes place will contribute to the amount of cycling that goes on in the aquarium.
In the overall scheme of things this may not make a big difference since cycling is going to take place anyway when rock and sand are introduced at the same time. If sand is added at a later date however this may affect the water quality and may result in stress on the animals.
Not much can be done since the sand will need to cycle and the material of organic nature will need to decompose. The process wii take place because we really have no way to "clean" the live sand and remove unwanted organic material without also disturbing the bacterial and other life forms that we want to be in the live sand.
The point I am trying to make is that it is important to be aware of the fact that live sand can indeed produce a primary or secondary cycle and that such can create stress on the animals.
The better the quality of the sand the fewer such problems you will have. Ideally you may wish to culture your own and avoid some of the problems associated with decay of organic matter present in commercial live sand. The NetClub librarycontains a long article detailing how to do so.
Some cycling will occur whether we like it or not. The degree to which it happens is what is important as that is what determines the level of stress that is created. Stress needs to be avoided as stress leads to more problems, often hard to deal with such as parasites in a reef tank.
Should you have any questions about this article feel free to Email Me.