I have a fairly extensive area of block paving as a front drive, etc but it
is on the north side of the house so it has a tendency to remain wet and
dank, and suffers from moss along the cracks and algie+grime on the surface.

I scratch off the moss with a blunt tool quite effectively but cleaning the
algie+grime is more problematic.

I have a pressure washer which will clean the algie+grime but it also brings
out the SAND.

any suggestions please for an effective treatment to kill and disolve the
algie+grime stains so that i can then wash off with lower water pressure??

thanks Ramon A