Avoiding a sandbed crash when moving tanks

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Hey,

I am swapping one tank out for another (same location) but new tank will be bigger and I was hoping for some pointers on avoiding a sandbed caused crash when doing this.

My plan of attack:
1) drain 50% display tank water into various water containers.
2) Relocate coral and as much rock as possible without disturbing the sandbed into seperate containers -e.g. coral in one bucket, rock in another.
3) catch all the fish and relocate them into their temporary home
4) drain remaining water while leaving sandbed as undisturbed as possible.

Here's where I get stuck... what should I do with the sand it inbetween removing the current display tank and putting the new one back together? Should I start fresh with new sand (not ideal)? Stir it up and ditch the water it's in but keep the sand?

Thanks