Black Moss

[Paver]

Came across a project that has heavy amounts of black moss on the retaining wall and patio (the pavers are actually slippery to walk on). Any ideas on how to clean this off besides some bleach and a heated pressure washer?

[gryan]

A cold pressure washer with a high gpm will take it off. Use bleach to kill anything remaining.

[Derek]

I would suggest hot water...for cleaning anything.
Bleach would be my first try.
If it won't get it all with that...they make mold and algae removing chemicals...although I have never needed them.