Why won't my tank start cycling? I bought live rock of a friend, well.... Maybe it was live. It had been out of water approximately 3 weeks. So I put it in my tank along with live sand and waited a week to see if I got an ammonia spike but it never came.so then I added a raw shrimp and I'm a week into it decaying and the levels are still the same. I just added a piece of live rock from my lfs today, is there something else I have to do to start the cycle?