Originally Posted by Magnus
As an add-on to my above post...I was figuring the detritous from the live rock would have cycled the tank on it's own?
That's entirely possible and happens often. But if it did, and then the bacteria didn't have "food" (ammonia source), the bacteria could've died off somewhat. And without test results during those 4 weeks it's pretty much impossible to know what was going on during that time.
Not saying you're destined for a cycle... just saying to keep an eye on it and not assume you won't see one.
If ammonia does start showing up, I'd do whatever water changes you need to, to keep it under 0.25ppm or so. Impossible to say how much of a water change that would be because of not knowing how high the ammonia would be. A good starting point would probably be 20% daily - that's what I've done when my quarantine tank needs a couple days to catch up.
Regarding the bacteria... you won't need to add anything - that's the cool thing. You'll get all you need from the air!