Do I need two water pumps for two radiators?

[Nada190]

I want to use two 480mm radiators, Alphacool XT45 and ST30 for my loop with only one cpu block, overkill I know but whocares.

Do I need two pumps or can I get away with one? It's a Corsair 900D, one rad on top and one on the bottom.

 

[xboost]

1 good pump will be enough, just buy from a good brand and get a high capacity one.

 

[Nada190]

1 good pump will be enough, just buy from a good brand and get a high capacity one.

How powerful would I need? Do I look at the lph spec?