Running pump and filter at night

[midmodonhillwood]

Does it matter if you run your system during the day or at night? Our house is eligible to have a rate with our utility company that would benefit with running the pool pump and filter at night instead.

We currently run it every day from 7AM-12PM. I can't imagine it would matter what part of the day/night you run it, but I wanted to ask the ask the pros!

Thank you!

 

[mknauss]

Not really. It may effect your skimming efficiency depending on when the wind blows. You will need to adjust when you add your liquid chlorine so the pump is running for awhile after the addition.

 

[Darin]

You may save money running at night or morning if you have varying electrical rates $$. My REC rate double here from 2 pm to 9 pm.

 

[Dirk]

It would matter more if your pool had equipment you don't have yet (but might someday).

I run my pump during the day because I have a saltwater chlorine generator and an automatic acid dispensing system. I want those consumables replaced automatically while they are most being consumed: chlorine due to the sun and the kids, and acid due to similar factors. Otherwise, if I only ran at night, I'd have to program the SWG and acid to build up during the night, so that there would be enough of a surplus in the morning to last the rest of the day. I prefer to swim in water with a minimum but consistent amount of chlorine and acid, rather than getting blasted by both in the morning and then be running low in the evening.

Similarly, I have to run during the day for my solar heater, which wouldn't work at night, of course.

So you'll save money now by running at night, but your pool won't be getting filtered or skimmed during the day. And maybe someday your SWG and/or acid dispensing system won't be quite as efficient.

None of these considerations are major. Basically, you try running at night, and if your pool stays clean and clear, then you're golden. You can consider the SWG and other systems if and when they ever happen.

And if you find that your water gets a little cloudy during big parties, or you're not quite getting the skimming action you need for a couple months in the fall, then you make adjustments to your runtime schedule on the fly. Maybe you run the pump for a few extra hours in the afternoon during a big pool party. Or switch to a different set of hours only in the fall. You don't have to have the same schedule every day of the year.

 

[DavidArmenB]

Mechanically, and in terms of water circulation, it does not matter at all when you run the pump. Ideally, if you had a VSP, you’d run it at about 1200rpm (~100W) 24 hours a day.

 

[1poolman1]

Does it matter if you run your system during the day or at night? Our house is eligible to have a rate with our utility company that would benefit with running the pool pump and filter at night instead.

We currently run it every day from 7AM-12PM. I can't imagine it would matter what part of the day/night you run it, but I wanted to ask the ask the pros!

Thank you!

Aren't you on PG&E power? Their "peak" hours run until 9:00PM. If you run the pump later, 2:00AM - 8:00AM at least, you also have much less to worry about if we have a freeze. Until I got a VSP, I ran my pool those hours from 1990 until about 15 years ago with zero problems.

 

[Dirk]

Mechanically, and in terms of water circulation, it does not matter at all when you run the pump. Ideally, if you had a VSP, you’d run it at about 1200rpm (~100W) 24 hours a day.

It terms of power consumption, that's mostly true. But practical pump RPM is determined by factors that are unique to each pool, there is no single "best RPM."

Heaters, like solar and gas, need a certain amount of flow (RPMs). That need would override all others.
Suction- and pressure-cleaners need a certain amount of flow (RPMs), most certainly higher than 1200. More like 2000+.
An SWG will require a minimum flow, affected by plumbing configuration. That can be 1200, but sometimes higher. Mine is 1500.
And skimming requires a certain amount of flow (RPMs) for best results.

Now that doesn't mean you have to pick one RPM (if you have a variable speed pump). Between some pumps' onboard scheduling options, or a pool automation system, you can have it all. Mine:
1500 for SWG.
2200 for heaters.
2800 for skimming.*
2200 for cleaner.
800 for freeze protection.

* I actually have two skimming speeds. 1500 is fine most always. But I have a "high-speed" skimming mode for polishing the water for an hour before guests arrive.

Point being, if your setup allows, you can have multiple RPMs happening during the day, and even different for each season. There is no one "perfect" setting for RPM, rather there might be many.

 

[generessler]

I read somewhere long ago that running during the afternoon is recommended to get some mixing because the top layer of water is where sunlight warms it and depletes the chlorine, so algae can bloom there even if average FC is fine. I have zero idea if there's any merit to this idea. There's a lot of voodoo pool info out there.

 

[Dirk]

I read somewhere long ago that running during the afternoon is recommended to get some mixing because the top layer of water is where sunlight warms it and depletes the chlorine, so algae can bloom there even if average FC is fine. I have zero idea if there's any merit to this idea. There's a lot of voodoo pool info out there.

I would say the chlorine is mixed well enough at night to make it through the day. It's why we use target FC values vs minimum FC values. If you run your FC in the target range, there would likely be enough of a buffer to counteract the effect you're describing, if in fact it actually happens at all. And it's easy enough to test. Run an FC test on water from 2' below the surface (which is where you'd take it from normally), then run an FC test on water scooped from the surface.

Now the warmer layer on top and the cooler underneath, from a comfort perspective, is a thing.

My pool had cold spots until I had eyeball returns installed. Between aiming those correctly and running my pump during the day, no more cold spots.

I should disclose that I have a PV solar system, so I don't pay for electricity anymore. Which is another reason I run my pump when it is most beneficial for the pool and its users. If you really want to beat the power company, that's the way to do it. My panels paid for themselves in a handful of years, and electricity is going to keep going up and up and up. So my ROI is increasing every year. It's a great investment if you have a pool and are relatively sure you're not going to move in at least 5-10 years. If it's your forever home, it's a no brainer.

 

[newdude]

I read somewhere long ago that running during the afternoon is recommended to get some mixing because the top layer of water is where sunlight warms it and depletes the chlorine,

I read similar back when that the surface / top layer has 0 FC during peak sunlight.

Thats a fun experiment for when it warms up. I will leave the pool off for a day and get a sample with a syringe (or such) at various centimeters and report back.