Moving the 30 gallon across town should be no problem. For my 29 and 20 gallon tanks, my technique was similar to wazzel's. I bagged up all the fish, mobile inverts, clam, and corals individually (except I put a peppermint shrimp in with a banded coral one..don't do that). I then threw out half the water, and put the other half either in water containers or rectangular tubs in which I placed any live rock with permanently attached corals in. I covered most of the live rock in very damp paper towels. All were placed in Styrofoam boxes. I also had additional fresh saltwater premixed and up to temp at my new apartment. From there is was as simple as setting the tank back up adding the old and new water and making sure the temp was ok. Then I re-acclimated the critters for about 30 minutes and put them back in the tank. I kept the sand bed in my 20 gallon tank intact and had no problems other than a brief cyano bloom, so I think a 30 gallon could also make it without the sand bed being disturbed. Just make sure very litle water is in the tank so it does not slosh around. This is kind of a hot potato topic (and also depends on what shape the sand bed is in, you might want to play it safe and ditch the sand bed). Also, the sand makes the tank really heavy.