Mysterious red dust on my roof

[Midnight Rambler]

You can put up a picture on imgur.com and then post the link here. I wouldn't necessarily rule out mold because it does sometimes form along drip lines on roofs.

[Carey]

Any picture loading system (inc flicker, photoshare, google, yahoo...amoung many) will do, just hotlink it by copying the link...

There are Rhodophyta (red algae) species that do thrive in/on buildings in humid areas, but usually start appearing in streaks & blotches... they can turn dusty during dry spells like we had the week prior to the Keaau parade... and can have a dark - black/brown appearance... but not normally real uniform unless a fairly flat slope...

The red cider dust may also appear if a downwind lot is having a lot of cinder work.... you may not be real line-of sight to that work, but the wind could carry, esp if this happened only recently while we were experiencing Kona winds (reverse of normal) - that work could be much farther upslope & the dust settled on your roof...

Course if you have any of the dust...looking at it under a scope could help ID it... but what fun is the speculation then!

[hotinhawaii]

It's red algae and some mold thrown in for good measure. It forms on TPO because is it such a cool roof material. The color reflects so much heat that it stays moist much longer than any other roofing here making it ideal for algae to bloom. One good solution (true for any roof mold, algae or lichen problems) is to install a zinc strip (available many places online) at the top edge of the roof. The rain water releases tiny amounts of zinc which will prohibit growth on the roof. Some asphalt shingles are manufactured with tiny bits of zinc in them for this very reason.
But if that doesn't work, my best guess is aliens. And for that problem, there is no where to run or hide!