That pump should be enough for your tank. You don't need a lot of water flowing back down into your sump and back up again. You should be aiming at 4-5X maximum turnover of your net water volume from your tank through your sump (unless you are going with a bare bottom method--I believe they like to employ high flow return pumps to wash most of the debris/detritus from the display into the sump and skimmer).
The main bulk of your flow should come mainly from closed loops, waveboxes or powerheads.
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32"x32"x20" Cube-ish tank
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