The nastiest sidewalk I've ever cleaned. It was furry, with about a 1/4" thickness of algae, mold, and mildew build up. the home owner was thrilled with the results. I had to use a lot of love to get this sucker clean. :weightlifter:
Bet that thing was slick when wet....... Did the cleaning leave those streaks etched into the concrete or were they already there? I can't believe somebody would let a sidewalk get that grungy... why not bleach and garden hose it every now and then?