Transfering tanks - have I thought of everything?

[John Vinson]

So I pulled the trigger and am upgrading from a Red Sea Max 250, to a Red Sea Reefer 425XL.  I'm not keeping any of the new tank livestock, and my old tank is in the same spot that the new tank needs to go.  I have a spare acrylic 45gal tank in the garage and I've been slowly using the water from my main tank's water changes to fill it about half way, then I'll start transferring most of my coral to it (I've also got spare equipment ready to go, to include a heater, wave pump, filter, lights etc).  Once I get my old tank empty enough, I can move it from it's current spot and I'll be ready to install the new one.  As for the new one, I have two 55 gal food-grade drums that I plan on using to take the old owner's water and sand in to immediately put back in the tank once it's in position (all leveled out, etc).  I'll then let it settle for a day or two, which will give me chance to get everything in the cabinet organized and sorted before I start bringing the livestock back in from the garage, and I shouldn't have to worry about the tank cycling again, correct? 

If anyone else has done this and has any recommendations, or knows of something I'm not thinking of, please share!   Thanks

[Bevo5]

I’m no expert and someone else will give you better advice- but everything I’ve ever read says to lose the sand and start clean there. The live rock is really all you need to prevent a cycle. 
 

the water isn’t even that important. There’s not a lot of bacteria floating around etc. if you’re keeping a bunch of Rock that will more than suffice especially since the bio load will be much smaller compared to the tank. 
 

also. A 55g drum of water weighs 440 pounds! 

[obrien.david.j]

My advice is about half way in the middle.  
1. keep about half the original water.  There is good stuff in it. 
2. yes, put in mostly new sand - but transfer something like 2-4cups of the old sand to seed the new sand bed.  

I like your plan overall, pretty sound.