Labor Day: when swimming pools turn green

So Labor Day is the official conclusion of summer in the United States.  Dress codes are strict and woe betide the hapless summer enthusiast still to sport whites now that the Fall has descended and the serious business of returning to work has begun.  From the thirty something floor of our office in a fine mid-town city, it is possible to see the swimming pools at the top of skyscrapers turn green as no one uses them, for they are now closed.  Some drain the pools, so there's a turquoisey gleam still to be had from a distance.  Others just leave the water and the vibrant green is also quite striking as mother nature and algae begins to work its stuff.  Apparently the form is to wait until Memorial Day when fresh chemicals are added to turn the water blue again.  There's something oddly disturbing and quite believable about such muscular economics that reminds me not to accept an invitation to a swimming party next summer.  Even if offered.