last time I switched tanks it was from a nanocube to a 30g so there wasnt very much live stock.What I did was set up my new tank with the exact same parameters as the old tank.The same sg the same temp the same ph.After that i took all the livestock out of my old tank put it in a bucket.Then I too the old liverock and used it to aquascape along with my new rock.It took like 10-15 min. when I was happy with it I installed the livestock where I wanted.HTH
-jorge