Measuring Gallons Per Minute for Variable Speed Pump

mattco · Apr 14, 2024

I'm considering getting my first variable speed pump, and wanted to check one of my initial assumptions about it. I've heard that in order to program it for optimal cost savings, I need to be able instantaneously measure the gallons per minute at any given RPM. Is this correct? If so, would a FloVIS meter or something similar work ok in the setup pictured below?

Newdude · Apr 14, 2024

mattco said:
I've heard that in order to program it for optimal cost savings

Nope. Cost savings are what they are.

Rpms or Gpms are what they are.

If skimming works down to X Rpm/Gpm, then you run X and save a ton over max speed. You run as slow as you need for any function and thats how you maximize cost savings.

mas985 · Apr 14, 2024

mattco said:
I'm considering getting my first variable speed pump, and wanted to check one of my initial assumptions about it. I've heard that in order to program it for optimal cost savings, I need to be able instantaneously measure the gallons per minute at any given RPM. Is this correct?

Nope. Where did you read that?

mattco said:
If so, would a FloVIS meter or something similar work ok in the setup pictured below?

Not really needed.

The way to setup a VS pump for lowest energy use is to set the RPM to the lowest possible while still performing the required tasks sufficiently. For example, there are minimum RPMs for where a skimmer or heater or other type of water feature will or will not work and it isn't always by GPM so your best bet is to experiment with different settings and see if the various equipment is working as it should (i.e trial and error).

The skimmer is usually the item that dictates minimum RPM. The water should be flowing over the weir door rather than around the sides.

For heaters, they will generally alarm and shut down when flow rate gets too low.

mattco · Apr 14, 2024

Thank you NewDude and Mas985. If I run it only slow enough that skimming is working properly 24 X 7, does this mean that I can rest assured that I'm turning over the water enough each day?

mas985 · Apr 14, 2024

Turnover is not important for sanitation and circulation.

Turnover of Pool Water - Further Reading

www.troublefreepool.com

mattco · Apr 14, 2024

Very illuminating, thank you. That does make things a lot simpler.

To answer your question, "where did you hear that?". I've seen it multiple places, the most recent being here:

How Many Hours Should You Run Your Pool Pump?

www.swimmingpoolsteve.com

Rancho Cost-a-Lotta · Apr 14, 2024

Determine Pump Run Time

To figure out how many hours you need to run your pump, you need to know how fast your pump works. You can find this here.

www.troublefreepool.com

Newdude · Apr 14, 2024

mattco said:
To answer your question, "where did you hear that?". I've seen it multiple places, the most recent being here:

Sorry. We don't get out much because so much of the industry advice is garbage. We pretty much stay here and assumed you got it here too. Lol.

But yeah. I had 80+ oaks on an acre a mile up the block from the new place that's wide open. Yet i need 3 turnovers for filtration at both houses, literally night and day apart ? Everyday ? Regardless if it's heavy debris in the spring or no debris in July ? Or no debris at all, ever, at the new place ? That's up the block from each other. How does somebody in TX need what I need, or Toronto? Or France ?.

If the industry picks a high enough # of turnovers, then they were right for everyone in the land. It doesn't matter you only needed 15 mins to mix the chemicals today with no debris. 3 turnovers 'worked'.