Please go back and re-read Ben's post above and follow his directions carefully. He knows what he is talking about and by following his advice to the letter, you'll have the best chance at getting this problem taken care of successfully.

Per Ben's directions above, you need to be chlorinating with trichlor pucks which will help the iron to fall out into your filter. If the ones you bought are the dual-action ones with copper, don't use them. Go and buy some plain trichlor pucks. (Bleach will add chlorine but will not cause the iron to fall out into your filter.)

Good luck and keep us posted how it is progressing.