2 half power pumps vs 2 full power pumps

[Nickmag01]

I want more redundancy in my tank. My tank recommends return pump flow of 750 gph. Want to upgrade to dual sicce pump. Was wondering if 2 pumps each rated at 400 gph would be better than 2 pumps each rated at 800gph. Pumps are adjustable so I would turn the 800gph pumps halfway down.

 

[Biglew11]

You need to calculate head loss. how high the pump has to pump. length of pipe diameter of pipe and number of elbows.
here is a link to a calculator. https://pentairaes.com/pump-calculator. this one has the flow rates in minutes.
its alot easier to dial the flow back on a powerfull enough pump than it as to dial a week pump up.