I moved my 120 twice in 2007. One lost 1 fish because he was hiding out in a piece of LR. You need a couple coolers, pump, tubing, garbage can, and plenty of towels.
1. Remove coral and put 1 per baggie (ask any LFS for free) into a cooler.
2. Remove all LR and put into a cooler.
3. Put empty garbage can on truck
4. Siphon water with pump and 50' tubing (Lowe's) or whatever length you need to get from tank to truck. Or you can manually haul 5 gal buckets since your tank is smaller. Keep as much water as possible. Keep about 4" of water in tank so that you can easily remove the fish.
5. Catch fish and put 1 per baggie and into cooler.
6. Siphon the rest of the water out in the sink-it's usually the poop filled water anyway. There should be no water left.
7. Scoop all of your sand into a bucket. A plastic hand broom pan works wonders.
8. Move empty tank.
9. Set up tank in place
10. Put sand back in
11. Put water back in
12. Put equipment back in
13. Put LR back in
14. Float fish bags and coral for 30 minutes
15. All fish and coral back in tank.
Voila! If you don't have enough water to run the overflows, just make sure your powerheads are at least on. I did that for 2 days until I had made enough water with my RODI unit to fill the rest of the tank. If you can have water on hand, that would be better.
I moved a 55 gal in 2005 and no losses too. That only took 5 hours. My 120 took over 11 hours to move! Whew!