This pond filter must be seen to be believed! Once the filter sponges have done their job and got blocked with dirt and debris an indicator pops up to alert you that cleaning is necessary. Simply turn the blue dial from \'pond\' to \'waste\' and the auto-cleaning mechanism re-directs the water away from the pond and towards the waste outlet. After a few seconds the motorised paddles clean the filter sponges whilst the dirty water is ejecting away to waste. Once it starts to look clean simply switch back to \'pond\'. That\'s it - Job Done! An audible siren kicks in after two minutes should you forget to switch the cleaning mechanism off or if a \'deep clean\' is required. NOTE: UVC bulb included.