Glass Shower Door Cleaner. Lemon Pledge. Spray on door and leave for 20 - 30 minutes. Scrub with A stiff scrubby or magic eraser. Rinse well. The lemon will break up the gunk and the oils will repel water and gunk for a few weeks. Do this once a month or more as needed. Caution you will need to wash the floor of the shower well after this or it will be slippery.