Ragtops 
  I've got a convertible with a black fabric roof.
 
 I have to park it under trees and, whenever it rains, algae drips off the trees onto the roof. Once on the roof, since algae is a living thing, the weave of the fabric seems to offer the ideal nooks and crannies for it to grow and there is now a faint green bloom all over the roof.
 
 Normal car shampoo doesn't seem to touch it, the only thing I've found will shift it is the power spray on a jet wash (but I don't want to go over my whole roof with that). I've had a squint in Halfrauds and other such places but I haven't seen any stuff to shift it.
 
 Has anybody else had this? Any ideas on killing the algae without bleaching the black top or going through the waterproofing?