Pumps can build pressure to lift water (measured in feet of head lift), or they can create flow (measured in gallons per hour – GPH). Pumps can also do a combination of lifting and flowing with their output power. If a pump uses more power for lifting water, it means there is less power to create flow. A pump Head versus Flow chart shows how a pump’s output flow will decrease as it uses more power for lifting. Hose/pipe length, reducer fittings, and elbow turns will increase head lift and therefore reduce output flow.