I just moved all the fish from my 18 to a 40 with same problem..the location was the same spot needed...
*First I half emptied and moved the 18
**then I moved their stand (and moved other tanks from larger stand)
***moved large stand to 18 location
_**_Started immediate tank set up because the 18 couldn't be plugged in from the coffee table
***I bagged my aggressives and dainties and put them all in a nice warm unused QT
with all the rest of the rascals
*****then I used the media and decorations from the 18 lightly washed in tank water and moved it all to the new tank. I put 3 used filters in there that i keep all in a 8 gal QT
I arranged everything and began the long task of filling
tested the warm water for any strange readings, waited to see if heater was proper..
**started putting fish in one by one. I'd scoop a fish in a betta bowl and flaot em with gradual water adding til the bowl sank and the fish was free.
I am sure there must be an easier way!
Looked like some kinda carnival get up.
Then after all that, I ended up destrying the tank water quality 2 days later searching for a fish and have now likely have no media left except the extra filter kind.