Abstract: A Wi-Fi tank monitor ultrasonically monitors liquid fuel oil in fuel oil tanks, as well as other liquids in respective liquid tanks. A transducer is magnetically attached to the bottom of a steel oil tank which will transmit ultrasonic pulses through the bottom of the tank and into the oil or other liquid. This wave is reflected by the top of the oil in the tank and be detected by the transducer on the bottom of the tank yielding the height of the oil or other liquid.