Tank is cycling very quickly?

Okay I set up my tank 3 days ago, there is 70lbs of dry rock and 10lbs of cured LR. there is 80lbs of dry sand and about 5lbs of LS...The first day I had ammonia from die off on the rock and the second day the ammonia went up, but today the ammonia went down and I have nitrite already. This is my first SW tank but in my previous experience with FW, none of my tanks have cycled this fast. Is it normal or is something off?

 

It is good for the amount of LR you have. It may bounce around a bit. I would test weekly. It will probably take 4 to 6 weeks to finish.

 

Okay, that sounds good. I also see a little coralline growth on some of the LR, is that normal.

 

It is if the conditions are right, congrats.

With the small amount of live rock you have I would only add 1 small fish every two weeks or so when the cycle finishes.

 

Would it be ok to add a pair of clowns at one time or is it too much? I figured since they are pretty hardy that it would be ok but now I am having second thoughts.

 

I would wait until you have added some other fish first and built up the bacteria. The damsels are pretty aggressive and should be added later anyway.

 

blue/green chromas are good too

 

maybe add a YWG?

 

What I am planning on getting so far is: Melanurus wrasse, mandarin, and pair of clowns...I am maybe thinking about a cardinal or something, Could I add a small cardinal for the first fish?

 

Yes but the tank needs to cycle first.

The majority of rock was dry, in 3 days you do not have a biological filter that would support addition of fish.

The tank IMO has not cycled or is close to it, unfortunately. Addition of any fish or inverts in the near future may prove disappointing.