Depends on wht type on sand bed you have. If its a non-functional shallow sand bed, by all means stir it a bit to clean it. However, if you have a dsb (deep sand bed), which is a functional sand bed, stirring it will cause the release of toxin gases into your water column. Easiest way to tell is if your sand bed is 4-6 inches deep, dont touch it, if its under 4, you should be safe