Methinks I had better tackle all the sand bed retrofit topics first.
Danial is right on the money when he says you don't have a cycle when adding inert sand to the bed. Cycles are only caused by die off of critters on the LR and LS. If you are adding Southdown then there shouldn't be any effect other than the sand storm. After about a day the sandstorm will have abated to the point where it won't bother the creatures in your tank. In the real reef storms and tidal events create sand storms all the time. The creatures from the reef get through them just fine.
The only effect that you might see is if you have an actively de-nitrifying bed. If you rearrange such a bed you disrupt the anoxic and anaerobic zones that have formed. This can lead to an increase in nitrates for awhile. That is why when you read through threads on RC you see people warning about messing with the bed. In a new, lightly loaded tank it should not pose a problem.
In a pinch you can slope the bed. Say make it 2" up front and 4" in back. It decreases the available surface area but in most cases it is not a major drawback.
When choosing sand you want a fairly fine, "sugar sized" sand. Crushed coral is too course for a proper sand bed. You see it used at the LFS but remember their tanks are only short term holding tanks so they don't worry about an active biological bed. As I stated earlier, silica sand, if it is fine enough, is probably OK to use. My own feeling is that aragonite is better due to the buffering capability of the calcium carbonate that forms it. There is somewhat of an urban legend that surrounds silica sands. It supposedly dissolves to form soluble silicates. There would have to be some pretty weird chemistry happening in one's tank for that to occur. I have heard some people mention that silica sand will react with fluoride in the water. That I guess is possible but it you are using RO/DI, like
all good reefers
then there shouldn't be any fluoride in the water.
NUBIANTANGLOVER,
That sounds fine for the lighting. There are plenty of good tanks out there that don't use MH. You want to use at least some 03 actinic in your lighting plan. Of course, there are some that say that isn't even necessary with modern high K bulbs.
Arachnidacolyte
I am going to talk about lighting next but don't have time do it today.
