When installing pumps in open-surface water installations at the water treatment plant, there are several issues that need to be taken into consideration. Firstly, it is necessary to use a flow sleeve around the pump, to ensure proper cooling of the motor. Secondly, there needs to be sufficient space between the pumps. Use the diameter of the pump including the flow sleeve as a guide for the distance between the pumps, the pump and the end wall, and the bottom of the pump and the floor of the tank.
You also need to ensure the correct NPSH (available and required), and this will vary, depending on the pump selection and operating conditions in the tank. We also recommend using a Variable Frequency Drive (VFD) for running pumps in parallel, together with a Multi-Pump Controller (Grundfos MPC). An even better solution is to use Grundfos Demand Driven Distribution, where pumping requirements are matched precisely to demand.
All this is covered in the video.