Fresh air is a vital commodity that cities in particular know how to value. Oxygen however is not just in demand above the water surface. It also fulfills important tasks in the water. Fish require oxygen to breath and microorganisms require oxygen to clean the water. Consequently, it is particularly important to always supply the pond with oxygen. Dead plants and fish waste are deposited on the floor as pond silt and bind oxygen. In winter a closed ice cover prevents the exchange with the surrounding air. To keep your pond in top condition throughout the year we recommend vacuuming out the floor silt as needed. The Pondovac 4 is ideal in this regard.