Will my tank cycle if I use established live rock?
Dose pure ammonia (places like Ace Hardware sell it, I've been told) to 4ppm and see if it goes back to zero within 24 hours. Dr Tim's also sells this (which is what I've always used. If buying from somewhere like Ace, you want it non-scented, no bubbles after shaking. If it goes to zero ( or really close ), you have enough BB and you are good. If there was die off, then there should at least be the end result of nitrates. Odds are, if you add fish slowly, you will be okay, but testing can't hurt.
Sent from my iPhone using Aquarium Advice