It is not a god idea to starve the pump by reducing flow to the inlet. Doing so will result in cavitation and damage the impellar. it is better to reduce the outlet side of the pump by partially blocking flow and putting a little back pressure on the pump. unless you have a positive displacement pump, this should not cause any problems. if you do have a positive displacement pump (piston pump for example) then you need to insert a pressure relief back to the suction side to control outlet flow. The power consumption difference on a small pump with partial flow restriction is insignificant.
