There is a buzz around here that the government is either giving an incentive to or requiring commercial pools have 3 speed pumps.
Presumably, you would ramp it down at night to save the planet.
I have not been able to nail it down yet but my first question is, has the health department rescinded the rule that the pump shall run at the rated turnover 24/7?

My next question is why 3 speeds?

The pool company who says it is true but is clueless as to anything about it. I assume this will require some kind of smart controller.

Has anyone heard anything about this?

This is what I came up with
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So it looks like it is only residential pools. I am still not sure how this saves energy over simply turning the pump off after you have one full turnover of the water which is what most pool timers are set to.

Never heard about it.
But all of your statements make sense.
Commercial pools require run time to keep the pools sanitized.
They could have 1 body or 200 bodies in the pool during the day.
On a residential pool you would need something other than time to determine when to change speed. Such as chlorine level.
So comes the smart controller
I recall years ago there were 1+ hp pumps for residential pools that had a photo cell incorporated in the pump.
At night it ran on low speed, during the day it ran on high speed.

So that makes some sense if you think about UV rays which break down the chlorine.

My pool computes to turn over in 6 hours and I run it 7 hours a day. That works out fine.

One of the inspectors on ECN from New Jersey asked his health department guy about this deal and he said the rule is they need 3 turn overs a day and the pump has to run 24/7 to keep the chlorinator going but if you could get 2 turnovers in 12 hours you could run the other 12 at half speed to get the third turnover.

I was thinking that there may not really be that much slack in the design tho. They could have just made it so you only get 3 plus a little at the rated speed. In that case there is not much saving to be had other than a more efficient pump motor.

I am really looking at the solar PV pool pump solution for my pool. I was just waiting to let the technology settle down a little and get some uniform testing standards. It is never good to be the first guy on the block with the next new thing.

Well it is just like any thing else today.
You can purchase a new water heater with improved insulation. That gives you a boost on efficiency. But the replacement cost far out weighs the savings on energy.
The same holds true. if you replace a 10 seer a/c unit with a 18 seer unit.
So if you are replacing it due to it failed then maybe.
If you replace it because you may save money on your electric bill. Probably not.

I doubt they will mandate anyone to replace an existing unit but I doubt it makes much sense, even on a replacement. You would be better off just buying as an efficient motor as you can get and running it on a timer for one turnover a day.
That part is addressed in the first paragraph of the law, if you can assume a capacitor start/run motor is the most efficient.
That is the only single phase motor left isn't it? I hope they aren't saying you need a 3p motor on a VFD. That will certainly move the payback period out into the next decade.

My caveat is faster pump speed may negate the VGB 2008 anti-entrapment design of the main drains. New FBC code allows flow rate design in lieu of air vents...