Go bare bottom
. But if you want to go with sand either rinse it until the water comes clear, or get new stuff. Anything you leave in the sand will most surely decay after the move, spiking nutrients. I rinse by putting about 2 gallons of sand in a 5G bucket and running a hose into the bottom of the bucket liquefying the sand. Swirl the hose around until the water comes clear. Give it a rinse in salt water after as it will be difficult for the salt to permeate down into the sand once back in the tank and you want to start that bio filter back up quickly
Dan