VEVOR Bio Pressure Pond Filter, Up to 2000 Gallons, with 13W UV-C Light, 1840 GPH, Pressurized Biological Pond Filter System Filtration Equipment for Fountain Pool, Koi Fish Aquarium Tank Garden Water

The water flow rate is not particularly relevant. The filter barrel is already fixed. Just choose a water pump that adapts to the filter barrel. A pump with a flow rate of about 2500L per hour is enough. The water pressure cannot be greater than the filter's capacity.

Reference pump: 2500 L/H 2.7m. Other depends on the size of the pool , please decide for yourself exactly how big to buy.