I've been told NOT to use a pressure washer on vinyl siding because the water can get behind the vinyl. This creates a mold or rot issue where you can't see it.

My cream-colored vinyl gets green every year or less. It's right next to the driveway so I can't ignore it. I usually get on a ladder and brush by hand, rinse with a hose. This year I wanted to avoid the ladder so I bought a cleaner that is attached to the hose. It worked pretty well. I applied it twice, brushing where I could reach. There are still some faint spots above my reach. If I get brave enough to climb a ladder, I'll get them too.

I think I'll use this stuff twice a year to stay ahead of the algae (green goo). It's sure easy to do. Costs about $8.