I use to keep an extra 2000 gph pump in my 350 gal pond just pointing to the side. I would run it for about 6 hrs a day to exercise my catfish. I suggested more than once on here that a round tank allows you to direct the waterflow in a circle. Creats kind of a whirlpool in a round pond, but with an inner wall like you suggest it would be more stream like. You could definitely see the whirlpool in the 350 gal round pond, and my big catfish would swim in one spot for hours and then rest in the center where the current was lesser. It was also great when it was bare bottom because all poo, and debris would rest in the center and made for easy scooping. Great idea so run with it. Fish love the circular water motion. You would need a huge tank if you were going to pump 100,000 gph imo. 2000 gph in a 350 gal was about as much flow as I would ever put in a tank that size. I'll be running between 10,000 and 12,000 gph in my 4000 gal tank(not round). I have plans for an 800 gal oval tank in the works that will incorporate fast circular movement though.
