Abstract: A tank cleaning unit is movable within a storage tank and applies cleaning fluid from a fluid spray nozzle onto accumulated sludge or waste in the tank to clean the tank under control of a control system located externally of the storage tank. The unit is moved by drive motors mounted a transport chassis of the unit with guidance from remote control to clear a path toward a desired position in the tank with the cutter fluid spray. The unit applies cleaning fluid to the interior of the tank to clean the accumulated sludge or waste. The unit includes structure to prevent tangling of the supply and control conduits and conductors connecting it to the remote control system. The unit also provides improved visibility in the presence of vaporous or foggy conditions within the tank during spraying, and is more maneuverable while in the tank.