In order to rub his face that raw he has been slamming into the walls of his enclosure or against something in his tank. Setting water out for 24 hours is not enough. 48 hours will remove chlorine, but it is safer to just buy a dechlorinating agent like Prime and treat the water with it. Takes very little Prime to treat a gallon of water.

You need to figure out what is causing his stress before he seriously hurts himself.