The smell you've noticed is the Live Rock going through a natural die off period. The Nitrogen cycle is a smelly cycle in the beginning but once you've established a good bateria colony to handle the waste load the smell will deminish. If you have uncured live rock the process will take more time. If you really can't stand the smell, a protien skimmer will help. When I cured my rock I put a protein skimmer on after the first two days because the smell was so bad, after the skimmer was on the smell nearly vanished.