The black streaks on your tampa roof are an algae called gloeocapsa magma. This Cynobacteria is transported by airborne spores. Once attached to the roof it begins to feed on the limestone found in your shingles. If left untreated it will continue to grow and spread until the roof eventually becomes black.
This fungus will cause your roof in tampa to deteriorate prematurely and it can raise your utility bill. You should never pressure wash a roof, it will shorten the life span of your roof and cause more damage as well. Apple Roof Cleaning Tampa uses a low pressure spray application to remove the algae safely, without damaging your roof or surrounding vegetation.
This happy Tampa customer thought that it was time to replace the roof, because of black streaks.