 Okay, so it's really a two-part solution here, Ed. First of all, what you need to do is to clean the moss that's there first. Now, there are deck cleaners that work very well. There are deck brighteners that work very well. These will both remove the existing moss that you have on that deck. Like regardless of how thick that moss may be, sometimes it's just sort of like a thin greenish tint, but sometimes there can be like almost an actual thickness of moss.