Oase Pondovac 4 Professional Koi Pond & Water Garden Vacuum System Dual-chamber Vacuum System: Two cylinders alternate suction and drain cycle to provide continuous suction. Sludge Drain with Drain Hose: Dual-discharge option for draining waste water directly into flower bed or attach debris bag and place into pond to "recycle" pond water during coarse debris removal. Use Drain Cap during wet-vac operation. Aluminum Extension Tubes: Lightweight bend-resistant tubes. Transparent Extension Tube: Allows easy visual inspection of debris material and to monitor operation. Universal Multi-Tool: Removes pond sludge without taking in pond gravel.