When running a pump, always make sure that it running as per the design duty point or near its maximum efficiency point in order to save power and save your pump to last longer.
To do so, all what you need is to install a pressure gauge on the suction pipe and a pressure gauge on the discharge pipe and modulate (close or open) the discharge valve so that the difference between the two gauges equals the required head.
from the pump performance curve, you can know how much flow the pump is giving for a certain head.

Note: Always keep the suction valve fully open, and control the head by the discharge valve only to avoid pressure drop in the suction pipe that may leads to pump cavitation.