What type of feed pump is recommended for a shallow beach cistern with the dimensions at about 10 feet and 3 feet wide? The cistern will be located on a beach near a lagoon and ocean.

The feed pump will be providing water for the water purification system from Danfoss called the Watercube. The flow rate needed for the feed pump is between 2 gal/min and 5 gal/min. The high pressure pump from the Watercube is a positive displacement pump so I heard that a centrifugal feed pump would be the best fit. Can anyone validate that?

The distance between the beach cistern and the water cube should be about 20 feet.

The lift of the feed pump should be around 40 feet.

The feed pump will be using power from batteries (size unknown at this point).

Looking at the SqFlex from Grundfos, the 25 SQF-3 Centrifigal pump looked like a possibly good fit. However, I was not sure if it would run properly at lower levels since it is meant for up to 16 gal/min. Also how much amperage does the pump draw? Is there any amperage surge at start-up?

The water will be salt water at about 35100 TDS. Therefore, the pump needs to be able to handle salt water.

The pump would be running around 15 hours or so per day.

Any recommendations on a possible feed pump for this project would be appreciated.