This gauge well mixer works off of the differential pressure in a storage tank and gauge well. Slot covers with dividers are installed in the gauge well. The slot covers and dividers are staggered for better mixing. The gauge well has a vertical interior space extending the length of thereof; wherein the slots open into the vertical, interior space. A first horizontal divider is located in the vertical, interior space below a first slot; and a second horizontal divider is located in the vertical, interior space above a second slot. The slot covers are installed on slots located between the first slot and the second slot.