Howdy! This is my first summer with an inground 20 x 40 pool sorrounded by neighbors' mature trees, creating an ambiance of relaxation in Alexandria, VA. We have installed a salt water chlorine generator and are finding that we need to shock the pool every 4-5 days to clear it from wall-clinging pollen. I will start taking and recording readings and see if there is a trend with the free chlorine and other chemicals. I thought the salt generator was the end of the chemical balancing act! Here to learn.