if the clone is small enough and hasn't rooted much in the soil, it IS possible to gently break/rinse off as much soil off as you can without damaging the roots too much. if the clone has rooted a lot already in the soil then there's not much you can do unless you want to risk hurting the plant. you have to be really careful and you inevitably end up with some soil in your hydro system. always use a filter before your pumps to make sure they don't get clogged.