A few months ago I bought a small pressure washer, 1300 PSI, and have used it for odd jobs around the exterior of my house. Today I decided to tackle a bigger job: washing away algae from my walkway, driveway, and sidewalk, that tint the concrete dark.
It was... very very slow. I think a 1300 PSI unit isn't quite up to that task, because I spent nearly two hours washing half of the driveway. Ugh! It was a very slow process because to wash anything off I had to use a pinpoint stream, and that meant a huge amount of repetitive back-and-forth. But what little I did clearly shows improvement.
The pressure washer is great for other things. My next project, to be tackled over a weekend or two, is to wash the patio and pool area. I've been lazy and haven't done anything in the two years I've been in my house. As a result, the deck and screen support beams have some algae and dirt accumulation. It isn't too bad but I know it'll look better when it is gleaming white and clean again.
I think I'll just punt the front area and hire a company to do it. One estimated the fee would be around $65, and for that I'll definitely just have someone else do it!