Umm, that could back fire on you. It depends, how dirty are we talking here? If you've never vacuumed you're sand bed before, if you disterb it you could release some nasty nasty nitrates and ammonia Into your system and kill everything. Id recommend a sand sifting goby and a big clean up crew. They will keep your sand clean. My diamond goby kept the sanded in my 180 spotless.