⚡【Aquarium Gravel Vacuum Works Two Ways By Plug In Or Rechargeable Use】Innovative patented design water changer,3 power supply modes can be selected, increasing the convenience of daily use：①It is used by plugged in ②After fully charged, disconnect the adapter and use it, and it can be moved freely without being restricted by the length of the cord and place.③Use while charging，while using, the battery will store electricity at the same time.Please fully charge before use. ⚡【Powerful Electric Water Changer,Use of the Site and Water Pressure are Unrestricted】Compared with the traditional siphon water changer, the new electric water changer can be used whether it is pumping water from high to low or from low to high, and it is not limited by water pressure.The water at the bottom of the fish tank can be pumped clean, there is no minimum water level. Free Your Hands,The motor controller with a clip ,can be adjustable according to the thickness of the fish tank. ⚡【3 Grades Adjustable Flow Rotary Switch，With Battery Indicator Light】Different flow grades can be adjusted according to different needs,maximum flow is 420GPH(1600H/L).We recommend that you drive to the maximum grade first and then lower the gear. This approach will quickly start the motor and increase the flow rate.You can follow the battery at any time through the battery indicator.It can be used for 2 hours when fully charged.