Hi, Mike. The normal mildew killer is household bleach. This really works well to kill the stuff and you can come back and wash the mildew off later. The problem with this is that you do not want to get the bleach in your eyes. Use a mix of 1 cup of bleach to a gallon of water and be sure to wear goggles over your eyes when you put the mix on with a sponge. Let this dry and then wash again with soap and water. You do not need to put a lot of water on for either process. Wring or squeeze the sponge to get most of the liquid out before you put the sponge to the ceiling.