I was in charge of a crew that used the Shark. It requires major use of the polar crane. Scotchbrite pads were stacked horizontally and a air operated motor rotated the pads in one motion to scour the walls. It covered a ~ two foot path with the Crane raising and lowering the Shark. There was also a "WEPA" device from a Swedish company (I think) that had rotating disks of Scotchbrite pads and it also required the polar crane. I remember a Tri-nuke filtration system that is entirely different but used a sh#t load of filters and acted like a pool skimmer.
