Pump Run Time

revv · Jan 31, 2023

I've heard that the entre water of the pool needs to go through the filter once per day. Typically, that means the pump has to run about 8 hours.

I've been looking at the equipment that was installed here to see if I can save some money. It turns out I have a Jandy VSSHP270DV2A pump which is in Jandy's "Commercial" pump section. To my surprise, this is quite a powerful unit. I looked at the manual and found this:

I estimate my pool size to be 10K gallons or so and the pump always runs at 3450 RPM, according to iAcqualink.

Without knowing the Total Dynamic Head and just going with 80 GPM (middle of the chart), that means that this pump moves 4,800 gallons of water per hour. Estimating even more conservatively and using 60 GPM, that means that it can move 3,600 gallons of water per hour.

Considering that I have a 10K gallon pool, heck, let's say 12K gallons to be safe, would it be safe to assume that I just need to run this pump for 3-4 hours a day? I've been experimenting all winter and running it 4.5 hours a day (the installer left it at 8 hours) and testing frequently and haven't seen anything happen to the water. It has been crystal clear for months now.

Is my math here right or am I missing something? I wonder if I could reduce run time even more to like 3 hours, but would like to get some opinions. I wonder if the math really is that straight forward. I could also leave it running longer at a lower RPM, but I'm not sure what the preferred option is.

Also, assuming I can run it for less time, I will need to crank up the SWG to compensate for the reduced running time, right? The installer left it at 80% and when I finally started testing myself I discovered my chlorine was at an insane 14 ppm. I've adjusted since then, always based on testing, and I've managed to keep it at 10-30%, most of the time staying between 15-20%.

For reference, here's the manual of my pump: https://www.jandy.com/-/media/zodia...5700.pdf?rev=a135e740888444e680a0d3d0a77ce28e

ajw22 · Jan 31, 2023

You have heard a commonly passed around myth about pool turnovers. Read Turnover of Pool Water - Further Reading

You only need to run your pump for a reason. That can be:

Mixing chemicals
Skimming the pool
Running a pool cleaner
Generating chlorine from your SWG

Otherwise pump runtime is personal preference. Some folks choose very short pump runtimes and others choose to run their pump 24/7.

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 · Jan 31, 2023

So to produce my needed FC, I *need* to run my pump about 12 hours in the peak season, and alot less in the early/late season.

Filtering and skimming is the opposite with more needed early/late and much less when all the crud isn't falling mid season, but it's a similar moving target.

In just under 2 hours if high RPM running, I use the same energy as running 24/7 on low RPMs. Doing so ensures the water is always moving and 95% of anything that lands in the pool makes it to the skimmers. With the pump off for 12-16 hours a day, that's alot time for any crud to get waterlogged and sink to the bottom.

When running the SWG for as short a time as possible, the FC will also swing at times closer to a liquid chlorine pool either from daily UV/FC loss, or an overnight storm blowing in organics. Running low RPM around the clock keeps the FC topped off for the most part, and ready for anything.

The other added bonus is that I get full time filtering and the thought of whether it's enough filtering never crosses my mind.

At most, $10 more in energy costs saves a boatload of work and makes pool care an afterthought most days. The convenience alone makes it worth every penny, and at times like the spring and fall when I'd need more than 12 hours filtering/skimming, it costs even less than the extra $10 a month to just run 24/7. I cannot reccomend it enough.

You certainly don't have to, but most of our pros choose to, for good reason.

revv · Jan 31, 2023

Thanks guys. I really appreciate your input as always.

I did a brief observation monitoring watt usage with iAcqualink at different RPMs and then converting to cost. Check it out:

My goal is to run this pump when my solar panels are generating power and electricity rate is lowest ($0.34/kWh). In the winter, that means I have about 5 hours to run the pump and in the summer that number goes up to about 10 hours.

I've been running the pump all winter for about 3.5 hours at 3,450 RPM, so about 7 kW/day which I knew was insane, but was too focused on learning pool chemistry to address this.

What is the definition of low speed? The reason why I ask is because at RPMs other than 3,450, my filter is not building pressure. The gauge falls below the "CLEAN" indicator. Is this normal? I have no problem running the pump 24/7 if it is quiet and if the economics work out, but I want to make sure I'm not breaking anything.

Is the SWCG affected by RPMs? Does it chlorinate less at lower RPMs or will it always chlorinate at the same rate, regardless of pump RPMs?

Lastly, based on the chart I posted in the first post, if I run the pump at 1,200 RPM I can move say 30 GPM or 1,800 GPH. That means I can run the pump for 6 hours at this speed and theoretically do 1 turnover at a cost of of $0.25 per day, almost 10x less than running the pump for 3.5 hours at 3,450 RPM.

Newdude · Jan 31, 2023

revv said:
What is the definition of low speed?

The lowest RPM that accomplishes your goal at that time. You skimmers / swg / heater will likely have different RPMs that they work well / turn on.

revv said:
Is the SWCG affected by RPMs? Does it chlorinate less at lower RPMs or will it always chlorinate at the same rate, regardless of pump RPMs?

It's either on or off, X% of the runtime you select. 24 hours at 50% equals 12 hours at 100% if the flow switch activates, it's 'on' as you set it to be.

revv said:
I can move say 30 GPM or 1,800 GPH. That means I can run the pump for 6 hours at this speed and theoretically do 1 turnover at a cost of of $0.25 per day, almost 10x less than running the pump for 3.5 hours at 3,450 RPM

Slow and steady wins the race, they say. Or. If you want to accomplish it quickly, then flow is king. But the environmental debris falling determins skimming and filtering times needed, not some blanket turnover advice. It's a moving target and simply running 24/7 not only is cheaper (or reasonably close), but it entirely removes both concerns as you're never tinkering with it. I bought my VS pump and SWG so that I could do less, I don't micromanage them if I'm skimming/filtering too much.

pjt · Jan 31, 2023

revv said:
the pump always runs at 3450 RPM

A VSP shouldn't run at it's top speed unless it's absolutely necessary. That negates all the benefits of a VSP.

revv said:
testing frequently

How are you testing? I don't see a kit in your signature.

revv said:
I could also leave it running longer at a lower RPM

This is a good option, especially since you have a SWG. I run my pump 24/7 at 1000 rpm (75 watts) and that provides enough flow for skimming and SWG operation. This costs me around $6 a month in electricity, and it's almost silent. I like the constant skimming, filtering, circulation, and chlorination. Enjoy the synergy of a VSP, SWG, and (hopefully large) cartridge filter.

revv said:
electricity rate is lowest ($0.34/kWh)

That's your lowest rate? Yikes! It's around $.13/kWh in Texas. What's your "high" rate? Where are you in California?

revv said:
my filter is not building pressure. The gauge falls below the "CLEAN" indicator. Is this normal?

Yes, that's normal. Pressure will fluctuate with pump RPM. As long as you have good flow from the returns and your other requirements are satisfied, lower pressure is better. For normal operations, the needle on my pressure gauge normally rests at zero.

revv said:
Is the SWCG affected by RPMs?

No, as long as the flow switch is closed.

revv said:
will it always chlorinate at the same rate, regardless of pump RPMs?

Yes.

revv · Jan 31, 2023

pjt said:
A VSP shouldn't run at it's top speed unless it's absolutely necessary. That negates all the benefits of a VSP.

How are you testing? I don't see a kit in your signature.

This is a good option, especially since you have a SWG. I run my pump 24/7 at 1000 rpm (75 watts) and that provides enough flow for skimming and SWG operation. This costs me around $6 a month in electricity, and it's almost silent. I like the constant skimming, filtering, circulation, and chlorination. Enjoy the synergy of a VSP, SWG, and (hopefully large) cartridge filter.

That's your lowest rate? Yikes! It's around $.13/kWh in Texas. What's your "high" rate? Where are you in California?

Yes, that's normal. Pressure will fluctuate with pump RPM. As long as you have good flow from the returns and your other requirements are satisfied, lower pressure is better. For normal operations, the needle on my pressure gauge normally rests at zero.

No, as long as the flow switch is closed.

Yes.

I'm using the TF-Pro to test regularly. Love that kit. In addition I use a Taylor salt test every once in a while as well.

Thanks for your answers. I could live with $12 a month to run the pump quite frankly and I wouldn't care. The problem is that right now I'm paying $75

I did some testing just now. Trying to see how low I can run this and I've discovered that at 2,400 RPM it will no longer pull enough to fill the pump's water basket? There are maybe 2 inches of air between the top of the water level and the lid. Does this mean that I might have a higher Dynamic Head than I thought and maybe the pool builder put this commercial pump to be able to compensate? Per the chart in the first post, the 2,400 RPM maxes out when you have 40 ft of dynamic head. There is some distance between the pump and the pool, but no real elevation gain other than what's normal.

I switched the pump to full speed and it filled up almost all the way. Here's what it looks like after switching to 3,450 RPM and letting it run for a minute or so:

pjt · Jan 31, 2023

revv said:
I'm using the TF-Pro to test regularly. Love that kit. In addition I use a Taylor salt test every once in a while as well.

Would you please add that to your signature?

revv said:
I did some testing just now.

How slow can you run the pump and still satisfy the SWG flow switch? Do the skimmers skim correctly at that RPM?

revv said:
no longer pull enough to fill the pump's water basket

Can you post photos of your equipment?

Newdude · Jan 31, 2023

revv said:
Trying to see how low I can run this and I've discovered that at 2,400 RPM it will no longer pull enough to fill the pump's water basket?

How high is the water level in the skimmer ? (Hopefully halfway up the face of it). Low water level may disrupt the normal weir door operation.

Also, If a weir door is sticking up, it may starve the pump until the water level drops low enough to force the stuck door open.

Newdude · Jan 31, 2023

revv said:
could live with $12 a month to run the pump quite frankly and I wouldn't care. The problem is that right now I'm paying $75

Mine with insane NY electricity is $20 a month give or take. As discussed above, I'd need at least $10 of that to run a schedule. We had the highest costs in the country forever, but sadly, most of y'all caught up and now 3/4 of the country has the highest rate in the country.

revv · Jan 31, 2023

Newdude said:
How high is the water level in the skimmer ? (Hopefully halfway up the face of it). Low water level may disrupt the normal weir door operation.

Also, If a weir door is sticking up, it may starve the pump until the water level drops low enough to force the stuck door open.

It's about half way up. I don't have a weir door though. When I look into the skimmer I see some water movement, but it is by no means a whirlpool.

Newdude · Jan 31, 2023

revv said:
It's about half way up.

OK great.

revv said:
I don't have a weir door though

You need one to properly skim and also keep any crud in the basket from floating out when the pump turns off. You can buy spring loaded replacements that will fit your dimensions.

But especially with no weir, you shouldn't be able to suck air. Are there any valves / actuators before the pump ? Got pics of the equipment pad ? How high is the pad in relation to the pool water level ?

revv · Jan 31, 2023

Ok, updating, I left for an hour and set the pump to 2,400 RPM. When I came back, the water level in the pump had gone down about an inch. Here's some video:

Here's a picture of the equipment. I can take more angles, just let me know what you want to see:

The pad is more or less level with the pool, maybe a half foot higher and there's quite a distance, about 75 ft.

I put the pump back on 3,450 RPM and the water rose and the air bubble in the tank is significantly smaller, in line with the first video.

Newdude · Jan 31, 2023

revv said:
The pad is more or less level

OK so the pump should have zero issues keeping prime at any speed. Normally any issues (low water level / suction side leak / etc) are exasperated by more flow, not less.

The only guess I have is maybe the check valve or actuator is malfunctioning. Hang tight for one of the plumbing gurus to chime in.

revv · Jan 31, 2023

Thanks. Hopefully someone will know what's going on. I also thought it was odd that it would fail to stay primed. This is a new system, installed in May of 2022.

mknauss · Jan 31, 2023

Acts like a downstream restriction. Caveat is low filter pressures. I would pull the cartridges from the filter, close up the filter, and see how it runs. Have the cartridges been cleaned lately?

revv · Jan 31, 2023

mknauss said:
Acts like a downstream restriction. Caveat is low filter pressures. I would pull the cartridges from the filter, close up the filter, and see how it runs. Have the cartridges been cleaned lately?

No, but I can clean them out today. Should I try that or would it be better to test without the filters in place?

Last time I cleaned them was 3 months ago and the pool hasn't been used since.

revv · Jan 31, 2023

Ok, updating.

I went ahead and pulled the filters to clean them. They weren't in terrible shape:

I opted for a quick hose down and they ended up like this:

I did find some rust on this thing:

Something interesting happened:

Pressure is now up!!! You can see in previous photos that it was closer to 12 psi before. Now it is back in line with what I had when the pool was new and pump running at 3,450 RPM.

The last person to open this filter was a Jandy-appointed service professional who came to swap out the inner metal ring since there was rust present and the system was 6 months old.

When I sealed the filter back up I made sure to carefully clean the entire o-ring as well as the surface in which it rests. I wonder if there was some kind of leak before preventing pressure from building up?

Started the pump back up again at 3,450 RPM and it quickly filled up to an even higher level than before. Reduced to 2,400 RPM and the water level ~~stayed the same~~ dropped. Pressure on the gauge dropped to 12 psi. I am now testing 2,000 RPM. I hope this fixes the issue

Edit: No cigar. At 2,000 RPM the water level drops significantly:

mas985 · Feb 1, 2023

Have you tried lubing the pump basket lid o-ring?

Also, check the o-ring for any cracks.

hillyjd · Feb 1, 2023

I found this Hayward tutorial on pump sizing a few years ago. If you really want to get into the math of pool pump flow.

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