Moss Out! is a remarkable non-bleach roof and walk moss/mold/mildew remover. It isn't as "instant" as bleach, but has a lot of advantages over bleach-based products. It is non-staining, does not damage vegetation (when used as directed) and, best of all, has a residual inhibiting effect that can last for a year or more! I've used this stuff and it's absolutely remarkable for removing mildew "streaking" on roofs.
JOMAX is an EPA registered mildewcide concentrate. It's unique ChlorRelease bleach activator magnifies the strength of chlorine bleach but at low concentration levels so it will not damage painted surfaces and can be used near plants and shrubs. The detergent cleaning system in JOMAX loosens dirt and stains, eliminating the need for scrubbing. To clean mildew-infected surfaces, liberally apply properly mixed JOMAX solution. When used as directed JOMAX will not damage painted surfaces, aluminum or glass and can be used near plants and shrubs.