Daf Yomi - Yoma 88 - Blessing Before Immersing on Erev Yom Kippur

The Tur (606) rules that when one immerses in the mikvah on Erev Yom Kippur he should recite a bracha first. The mefarshim ask that 'tevilas ezra', the requirement of immersing in the mikvah after one saw keri has been nullified so why would there be a blessing first? Rav tzvi Pesach Frank posits that since the immersing on Erev Yom Kippur was always cusomary and there never was an interuption in this, it is considered like the original established decree is still intact and therefore there is a blessing beforehand.

The Rosh brings from Rabbeinu Sadya Gaon that after immersing one should recite a blessing. The Rosh disagrees and maintains that there is no blessing because there is no obligation. Rav Shach writes that even though there is no obligation, but when a person immerses himself he is fulfilling a mitzva and now would be able to enter machane leviya if there would be a Beis Hamikdosh. This would be analagous to reciting a blessing on shechita. One is not obligated to slaughter an animal, but if he does he is fulfilling the din of the Torah which is permitting an animal for consumption through shechita. He concludes that according to Rabbeinu Sadya, this blessing can be recited any day of the year that one immerses himself due to keri.