Ok, so take buckets and rinse, rinse, rinse, etc.
Remove fish to a bucket. Remove 50% of water in tank.
Turn filter off!
Take plastic dinner plate (never seen soap) and lay it kitty corner against the side of the tank, one edge near bottom, one edge near top of tank.
Let the sand slide down the plate and onto the bottom of tank. You can arrange with your hands after it's in there. This helps keep the cloudiness and possible filter problems down.