I have tan colored shingles on my roof. The roof is about 8 years old. The high humidity here is a perfect breeding ground for mildew stains on the roof. In hindsight, tan was a poor color choice. I have heard about bleaching with Clorox followed by a clear, breathable sealer to prevent regrowth. I can't do the job myself and would like to hear from anyone who has had this done and about reputable firms in the Houston area that perform this service.