A sand bed hold lots of nutrients in it. I would not reuse a sandbed. You may want to use some of it to seed an new sand bed. My experience is that once a sand bed full of worms and life was disturbed, it will take a long time if ever to become stable again. Of course how bad this is depends on how full of nutrient it is. Imported live sand from the reef do not really hold anywhere near as many animals as the sand typical of our tanks.