Abstract: A device and method for cleaning the interior window surface of an aquarium comprises a buoyant floatable interior element and an exterior element. At least one element has at least one magnet and the other element has a material attracted to the at least one magnet so the elements attract each other under the influence of a magnetic force between the elements. Such material may be a magnet or magnetically attractive metal. Movement of the exterior element along the exterior window surface of the aquarium causes the buoyant floating interior element to move along the interior window surface of the aquarium thereby cleaning the interior window surface. Once the magnetic force between the elements has been removed, the buoyant floatable interior element floats to and on the surface of the liquid medium present in the aquarium.