1,108. Mikvah Night
161:20 If a woman has tightly matted hair that cannot be separated, it is not a chatzitzah. Even if there are some stands that cannot removed, if they aren't visible from the outside, they are not a chatzitzah.
162:1 If her husband is in town, it's a mitzvah for the woman to go to the mikvah at the proper time so that they should not disregard the mitzvah "to be fruitful and multiply" even for one night. We see that Joshua was punished for causing the people to defer this mitzvah for one night. If a woman intentionally delays immersing in order to distress her husband, the punishment is very severe.