when I set up my new 72G, I used my old 42G rocks, water, sands and corals, and filter (MAG 350). I let it ran for 2 days, then put all my inverts and corals to the new tank (since I was using the old 42g as my QT (for all my fish got ICH)). it has been more than a month, still no visble signs of cycle. (i don't think it will happen anymore)
(all the inverts, shrimps and corals are doing fine in the new tank, and my old 42G is just out of Hypo now)
Wid