When a fountain is clogged, the spray may appear weak, uneven or go up and down. Unfortunately, occasional clogging of a fountain is unavoidable. Even when managed well, a body of water will likely have some amount of algae growth and/or vegetation which can get sucked up against the screen causing the fountain to clog. Debris from the surrounding area, both man-made and natural, such as plastic trash bags, grass clippings and leaves from surrounding trees can also contribute to clogging.