Well your gonna definately stir up lots of nitrate and hydrogen sulphide. What I would do and what I have always done and had good results is one of two things.Syphon all water out of the tank, and save some of it. Once the water level is down to the sand bed, dig a hole through sand so it exposes the glass bottom....preferably in a corner. If yu can tilt the stand with tank on it even just an inch or so on the back do it, so that water will all run to front corner better. It will take a bit of time but it will all eventually flow thorugh the sand to that spot you cleaned out. Syphon out what water collects and continue to do so until it stops filtering through. The tank needs to be emtied of all live rock which needs to be placed in the tanks original water etc in a separate container. The tank can now be moved on the stand with sufficient help, or in some cases depending on how big of a tank it may even be able to be slid on to a piece of plywood and moved. If not, just remove some sand from one end of the tank to reduce weight and not disturb the balance of the wsand in the rest of the tank. I think if the sand is replaced right away, along with live rock you should be fine. YOu can always was the sand yu removed with the water yu took out of the tank to reduce nitrates etc and whats left in the restb of the sand in the tank will easily repopulaate the sand that was removed and washed. I have helped the lfs here move large tanks up to 180 gal already since he did not have a pickup truck and relocate them to another house etc and set them backup and this is exactly what we did to move it, and have not had any problems. A mini cycle of very short duration at most which did not get to any levels to do any harm.
I htinnk if yu remove all sand then yur going to really stir up the nitrates and hydrogen sulphide, so then I wuld probbaly wash that sand really well before putting it back in the tank. I would however hold back a few cup fulls of sand, amnd keep it just as it was removed form the tank.
