Now water - based planting methods are more and more common. However, how big a pump should I get is one of the most frequently asked questions by a new hydroponic grower. But the truth is, there is no one specific answer for everyone. There are too many variables in how people design their h diving fountains and pond pumped storage systems, so there is a clear answer that can be applied to every situation. The only solution that works in all situations is to buy a larger pump than you think you need, because you can always reduce the water flow, but you cannot do anything to increase its maximum flow.
But it's actually not that troublesome. Once you know the minimum gallons your system needs to pump, it is easy to choose the pump. But we recommend that you choose a pump that can pump at least twice the water than the minimum gph you need. This will give you some flexibility in how to set up, future changes, and ensure that the pump will not fall below your expectations.
If necessary, you can easily reduce the flow of the pump, but you cannot make the pump larger than the designed flow. Most pumps have a built-in flow restrictor, which is just a lid that can be slid / rotated onto the inlet opening to reduce the inlet size.