A tank cleaning device is provided, comprising a base member; a conduit attached to the base member having an inlet, an upper outlet, and a lower outlet; and a plurality of adjustable legs connected to and extending below the base member. The inlet of the conduit accepts a cleaning fluid, and a cleaning nozzle is attached to either the upper outlet or the lower outlet. A method of cleaning the tank is also provided, comprising placing the mounting device at a first location, spraying the tank with the cleaning fluid until a selected portion of the tank is cleaned, discontinuing the supply of cleaning fluid, and then repositioning the mounting device to a second location within the tank and resuming the supply of cleaning fluid. Multiple mounting devices may be employed and periodically repositioned within the tank to achieve quick and effective cleaning.