perhaps you can explain why you want to change the sand bed? I would suggest leaving it as it is, but get cleaning crews ; turbo snails, sea cucumbers sand shifting starfish, golden head gobies, red and blue legged hermit crabs,and let them " sieve the sand" if yours isn't that bad.and maybe you are experiencing diatom bloom.Also focusing your pump heads to the sand may help as well just enough no to rake the sand too much