safe to add Live rock?

Is the rock you are planning on using cured or uncured?
Will there be a lot of life on it that you want to preserve?

I recall from another post of yours that you have fish in already?

To spare them further ammonia and nitrites you will either have to cure any uncured rock in another receptacle, or buy well cured/fresh aquacultured and monitor parameters carefully.

If *I* were going to add live rock to an established tank, I would keep it in a garbage can w/powerhead for at least a couple of days to check for ammonia- and that is if it looks and smells fresh.

Sometimes live rock is very fresh (i.e. Tampa Bay Saltwater aquacultured rock) and won't set up much of a mini cycle at all- other times it reeks of dead animals and needs to cure for a couple of weeks before being added to a tank with inhabitants.

Like any other question in marine tanks- "it depends"- this time it depends on the source of the rock.