If you put any fish in there within 6weeks I'm assuming that they died because of your cycle. What do you have for a filter? 20lbs of live rock is not enough for a 120gallon tank, it would take longer for the cycle to finish with that little amount of rock. I agree tha "they're all good" means nothing, it depends on what your definition of good are... so posting them lets us know.
:dive2: