There are pros and cons using reefer live sand.
1. Pros (you will inherit the good bacteria from the live sand which take times to cultivate if you start a brand new tank.)
2. Cons (At the same time, you might also inherit the hidden nutrients that come with the sand and most of the time was not disturbed. Now that it is distrubed, the level of spike might be high.)
Just my 2 cents...any other chip in...