Miz, everyone does it differently, I have the same shape as you just larger scale. To keep water movement good on the top and no "icky build up" in the corners, as well as good movement in the tank I have my pumps on the side where my output is. Pumps and output in the same directions or towards the glass side (closest).
Only on that side then the overflow is more on the other side altogether. So its kinda making a little whirlpool. If this makes since, I hope it helps.
Two on the back glass, one on each side, both pointing toward the middle and aimed slightly up so as to disrupt the surface. I'd put the left one somewhere in the upper quarter height-wise, and the right one about halfway down. The third one I'd go low on the left pane behind the rock so as to keep cr@p from accumulating back there. Which model goes where... I say a little trial and error is the best way to see what works for your tank, scape, and livestock.
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