Looking for advice of 2 speed vs using 1 speed on a timer

[landscaper]

I am looking for a new pump/filter for our pool. I keep reading about the energy savings of a 2 speed versus 1 speed. Aren't all pumps measured the same as far as volume of water they pump though? Am I missing something as I feel like I could run a 2 speed on low a lot, or a 1 speed on high with a timer for far less time. Wouldn't it work out to be similar in electric cost if they both filter about the same amount of water?

looking at either:
Hayward CC15093S Xstream Full-Flo 150-Square-Foot 1.5 Horsepower Filtration Filter
Hayward CC150932S 150 Square Feet XStream Above Ground Full-Flow Cartridge Filter System with 2 Speed Power-Flo Matrix Pump

thanks for any help!

 

[ping]

A 2-speed pump will save approximately 1/2 the total energy compared to a single speed motor for the same amount of water pumped.

This is explained in the Hydraulics 101 sticky in the Pumping Station forum. Part of that sticky is:

For example, low speed of a two speed pump has about 1/2 the flow rate as high speed and the affinity equations tell us that it requires only 1/8th the power of high speed. Unfortunately, two speed motors lose about half their efficiency at low speed so the energy use is only about 1/4th of high speed but still significant. So even though low speed needs to run twice as long for the same turnover, it will still save over 50% in total energy.

 

[landscaper]

Didn't know that, thanks!

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Do you have any thoughts on the above 2 pumps/filters? There was also a similar Pentair PNCC0150OF2160 Clean and Clear Aboveground Cartridge Pool and Spa Filter System, 1-1/2 HP.

I have a 27 ft. above ground round, the typical 4-4 1/2 ft. depth. I estimated around 19000 gallons.