Clorox will do the job and it is my preference. You need to scrub the area as well with a brush in order to REMOVE the mildew. Bleach ONLY kills it. What ever you do the only safe thing you can mix with the bleach is liquid laundry detergent (spray bottle use). Any thing else may put you in a position where your last worry is mildew. Lastly, rinse the area well with water and you are ready to go.