Had my water tested at the pool store. They told me it had iron and I need to use a metal remover. They only do a basic yes or no test I didn't get a ppm count. I had the water trucked in so I assume there isn't all that much iron. I would rather remove it than continually have to add a sequestering agent. If I shock it and it turns brown will it eventually clear up with my DE filter or will I have just screwed the water up completely? If I use the sequestering agent how often will I need to re-apply?