If you have a water feature that may only be a vertical lift of 10' and you are using a pump that is designed to push 30'-40' then you can load the motor of the pump causing it to run inefficiently. By loading the motor you use more electricity which in turn produces more heat and shortens the life of the pump. In order to alleviate this problem and lower the head pressure of the pump you can add a valve at the discharge of the pump. Fountain heads, biofilters, skimmers will also reduce the head pressure. This will help the pump to run cooler, more efficiently, and extend the life of the pump.