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Can you tell us what kind of filter it is? Many have a flow control valve on them to cut back on the flow. Also, good water movement is good, and it might just be the sand needing to settle a bit. Often sand will fly around the tank a bit when it is newly placed, but if you have a lot of turbulence in the water that is not good for the fish, as you suspect.
Have you considered cycling the tank without fish, by using household ammonia? This will give the tank time for the sand to settle and accumulate healthy bacteria prior to introducing your angels. I know you did not ask about that, forgive me!