1,094. Finding a Stain During the Seven Clean Days

159:8 The self-examinations must be performed by daylight and not by candlelight.  Some are stringent even after the fact that if there wasn't at least one examination by daylight on the first day and one on the seventh day.

159:9 If the woman found a stain during while counting the clean days, or even if she saw actual blood, she can make a hefsek taharah and put on white undergaments that same day before twilight. The next day she starts counting seven clean days again.