Doesn't matter what happens outside your intent, visualisation. You do your best in concentrating in making your visualization powerful and feeling it, with confidence and certainty. Apply it a couple of times, and be assured it is as done.
If you meditate and do it this way, don't forget to acquire a little bit of trance. And also do the foundation meditation. This will help actualize your cleaning in a better way and you'll learn to feel the energy and cleaning taking place.
Good luck