PondSweep® skimmers pioneered the use of bottom drains in water gardens to improve circulation, filtration and water clarity. They act like pond vacuums, continuously sweeping the bottom of your pond or wetland. PondSweep Bottom drains help combat algae by removing more pond nutrients, reducing the need for full pond draining and cleaning at the end of a season. Our high-efficiency bellows significantly improves the performance of our bottom drains.