【Quickly Change Water 】just use a long flexible hose and 2 flow valves, you can change the aquarium water more quicker and easier, no need electric, it's semi-automatic water changer suitable for medium and large fish tanks. No spill, no mess and no heavy lifting for changing dirty water and adding clean water 【Aquarium Gravel Cleaning 】When you use this water changer to suck away aquarium dirty water, you can move the gravel tube to cleaning the gravel or install the duckbilled on to clean fish feces. With the pressure from the water, the gravels and sands can be sucked up to the gravel tube then to vacuum out the debris in gravel 【Non-electric & Quiet】this aquarium water changer is not electric, no noise no disturb to your fish or plants. All you need to do is to control the 2 valves and open the faucet. With 2 orange built-in control valves on the water changer, to turn it on or off you just need to rotate the valve by 1/4 turn up or down. To add clean water in to aquarium, please remember to keep the water flow assembly valve closed, so when you open the faucet the water will flow into the hose