Is this a dumb idea with Variable Speed pump?

[caseyrichards]

Hey everyone!

Been stalking this forum for about a year for some really great pool tips. Decided to finally join and ask my first question because I haven’t seen it answered this way yet.

I have a Pentair SuperFlo VS pump. When it’s running at full speed the PSI on my sand filter reads 15 and my flow gauge reads 65 gpm so that’s 3900 gph. Now if my pool is roughly 25000 gallons give or take then that means the pump should theoretically be turning over all the water in the pool one time every 6.5 hours when run at max speed. Feel free to keep me honest on the math above.

So here’s my question: why can’t I just run it at max speed between the hours of 11p-7a (that’s the super off peak electricity time in my area with the lowest price)? That would be 8 hours in all which is even a little more than I need for one turnover. And then just set it to turn off between 8a-11p before it starts this all over again.

Don’t get me wrong I completely understand doing this basically means I’m operating my variable speed pump the same as a single speed pump. However if it’s restricted to just those hours at the lower electricity rate is it really all that bad in the end? It would certainly save the hassle of calculating the different speeds and hours to run it during the day to turnover the same amount of water.

Thoughts?

 

[mknauss]

Welcome to the forum!
Turnover is a myth.
You run the pump for a reason. First is to create (if you have a SWCG) or distribute (if you are adding liquid chlorine each day) chlorine in the pool each day. Next is to skim the surface.
You have a VS pump. The smartest method is to run it at the lowest rpm to skim your pool. How long depends on how much debris you get in your pool. Just be sure the pump is running for an hour or so after adding your chlorine each day.
Your VS pump at a low rpm uses about 1/8 the electricity it does at full rpm.
I suggest you read ABC's of Pool Water Chemistry.

 

[Jimrahbe]

Casey,

Welcome to TFP...

I run my 3 HP IntelliFlo 24/7 at about 1200 RPM for less than $20 bucks a month...

As Marty points out, the idea that you must "Turnover " x amount of water per day is just a myth... Chemicals keep your pool clear and sanitized, not how many times water passes through your filter. The filter is there to capture the junk that falls into your pool, not to keep you from getting algae..

You can run your pump the way you want, but to run it to meet some mythical turnover number just does not make much sense to me.

In my mind it is best to run a VS pump at a low RPM, rather than a high RPM..

You should take a look through our Pool Schools and see what we are all about...

ABCs of Pool Water Chemistry


Thanks,

Jim R.

 

[Panzer]

Well said Jimrahbe. I run my 1hp Powerflo LX pump 24/7 as well. While I would prefer a VSP (or even 2 speed)... the cost is pretty negligible in the scheme of things.

My question to CaseyRichards... You could've saved a significant amount of money by going with a single stage pump, if that's how you wished to operated it. As Marty pointed out, why not take advantage of both the low electrical rates at night AND the benefits of your VSP (keeping the skimmer fed & distributing sanitized water)?

If it were me.. I'd opt to run it at 65-75% of max overnight to help distribute chlorine, etc and then drop it to the lowest setting the remainder of the time. You may find your pool maintenance (vacuuming, etc) is reduced and your pool chemistry more stable. More time enjoying your pool and less time working on it, may outweigh any potential cost savings for you.
Hopefully, you find your happy medium.
Respectfully,

 

[cowboycasey]

Lower and slower is the key here.. it helps the pump, filter, filter media, and your pocketbook.. all great things..

I run mine at 1500 rpm 12 to 14 hours a day now to add chlorine from my SWG and to skim the pool... My VS pump is using 120 watts running so a 120 watt light bulb, that is it..

Do you have a certain time you electricity costs more, ours here in OK is between 2 pm and 7 pm... Just turn off the pump during those times and run it on low RPM when its off times

 

[caseyrichards]

Thanks for the quick replies! Good to hear about the turnover myth and not to worry too much about that. And I understand what the differences are between single speed and VS technology. So I guess my follow up questions are:

1. If I instead run my VS at a low RPM 24/7 isn’t that essentially the same thing as making it a single speed pump too just at lower electricity?
2. Do you really think there’s a huge cost savings between running it 24/7 at a low RPM and full speed for just 8 hours of restricted to only during those super off peak hours?
3. So when would I use the higher RPMs based on this new approach?
4. If I don’t have a SWG that requires a constant flow then what speed/PSI should I be aiming for 24/7? At max RPM the PSI on the sand filter is normally 15. If I shift the speeds down then it too drops. Some lower speeds don’t even register.

Many thanks,
Casey

 

[caseyrichards]

Well said Jimrahbe. I run my 1hp Powerflo LX pump 24/7 as well. While I would prefer a VSP (or even 2 speed)... the cost is pretty negligible in the scheme of things.

My question to CaseyRichards... You could've saved a significant amount of money by going with a single stage pump, if that's how you wished to operated it. As Marty pointed out, why not take advantage of both the low electrical rates at night AND the benefits of your VSP (keeping the skimmer fed & distributing sanitized water)?

If it were me.. I'd opt to run it at 65-75% of max overnight to help distribute chlorine, etc and then drop it to the lowest setting the remainder of the time. You may find your pool maintenance (vacuuming, etc) is reduced and your pool chemistry more stable. More time enjoying your pool and less time working on it, may outweigh any potential cost savings for you.
Hopefully, you find your happy medium.
Respectfully,

VS pump came with the house from the prior owners.

 

[mknauss]

Since you have no SWCG, and are adding liquid chlorine every day, run the pump in the low cost times. If low rpm sufficiently skims the pool, then run at low rpm all the time it is on. Be sure you add your chlorine when the pump is running.

Single speed motors cannot operate at low rpm. One VFD motors can.

 

[JJ_Tex]

Since you do not have a salt water generator, figure out the lowest speed you can run where the skimmer weir doors are still functioning. I would use that rpm as your baseline, then bump it up when it makes sense.

Here is how I have mine setup. It spends most of the day at "Pool", which uses 86 watts which is nothing. Then a couple times a day I have it kick up to higher RPMs (skim high and skim medium) to increase the skimming and water movement.

 

[caseyrichards]

Lower and slower is the key here.. it helps the pump, filter, filter media, and your pocketbook.. all great things..

I run mine at 1500 rpm 12 to 14 hours a day now to add chlorine from my SWG and to skim the pool... My VS pump is using 120 watts running so a 120 watt light bulb, that is it..

Do you have a certain time you electricity costs more, ours here in OK is between 2 pm and 7 pm... Just turn off the pump during those times and run it on low RPM when its off times

2p-7p is peak here too while as I mentioned above 11p-7a is super off peak (so that’s the only window I’ve been running it right now for lowest cost).

 

[mknauss]

as I mentioned above 11p-7a is super off peak (so that’s the only window I’ve been running it right now for lowest cost).

That is fine, but be sure you are adding your liquid chlorine within that time frame each day.

 

[caseyrichards]

That is fine, but be sure you are adding your liquid chlorine within that time frame each day.

You all keep mentioning liquid chlorine. We have a Hayward inline chlorinator feeder so is that the same thing you mean because that runs automatically the pump is on and I don’t ever add additional liquid or granular chlorine besides sticking those pucks inside that it takes?

 

[cowboycasey]

running it at night will keep the pool colder and the water "may" have a higher chance of getting algae as the water is not moving while the sun is on it...

lets try this for the weekend..

Run your pump at 1200 rpm from 11pm at night to 1pm in the afternoon.. that should be about 80 to 90 watts being used..

on Sunday see how your pool water looks.

did it skim like you want?
were there bugs on the floor?
does the water look clearer?

your filter works better at low rpm so it may be clearer than what you have had..

 

[mknauss]

You all keep mentioning liquid chlorine. We have a Hayward inline chlorinator feeder so is that the same thing you mean because that runs automatically the pump is on and I don’t ever add additional liquid or granular chlorine besides sticking those pucks inside that it takes?

OK -- so if you are using Trichlor, you may need to run your pump longer to add the chlorine needed to keep the FC level within target for the CYA level. See FC/CYA Levels

The chlorinator is an erosion feeder. So flow through it is needed to add the FC, which also adds CYA and acid.

Your CYA will be continually rising, which means your FC target needs to continually rise.

When the CYA gets to 60 ppm, you will then need to drain 1/3 to 1/2 of your pool volume and start over.

 

[cowboycasey]

You all keep mentioning liquid chlorine. We have a Hayward inline chlorinator feeder so is that the same thing you mean because that runs automatically the pump is on and I don’t ever add additional liquid or granular chlorine besides sticking those pucks inside that it takes?

Ohhh no... You have the devils candy, the fast food for pools... you can live on them but it is going to cost you in the end... 1 to 2 times a year you are going to have to empty up to 1/2 of your pool water.. if that is ok by you then keep doing what your doing..

If not you will want to do 1 of the following things..

1. change to TFP and start using liquid chlorine..
2. change over to a salt water generator...
3. keep using pucks..

All 3 cost the same for chlorine after 5 years...

1. is the easy but must be done every day
2. is the easiest, the SWG makes the chlorine for you and you just have to run it and the pump a certain amount.. this is also an up front cost that gets people at first... If mine died today I would have another one ordered tonight..
3. will cost more because of pool stores and water exchange

 

[caseyrichards]

Ohhh no... You have the devils candy, the fast food for pools... you can live on them but it is going to cost you in the end... 1 to 2 times a year you are going to have to empty up to 1/2 of your pool water.. if that is ok by you then keep doing what your doing..

If not you will want to do 1 of the following things..

1. change to TFP and start using liquid chlorine..
2. change over to a salt water generator...
3. keep using pucks..

All 3 cost the same for chlorine after 5 years...

1. is the easy but must be done every day
2. is the easiest, the SWG makes the chlorine for you and you just have to run it and the pump a certain amount.. this is also an up front cost that gets people at first... If mine died today I would have another one ordered tonight..
3. will cost more because of pool stores and water exchange

Haha! I like that analogy. It too came with the house and yes I’m considering ditching it for a SWG (just not sure what to do with it once it’s replaced as that would be a waste of a perfectly good unit plus the up front cost of the SWG).

 

[caseyrichards]

P.S. you also may want to consider updating the account settings when it asks for chlorine since there’s only two options to choose from Liquid or SWG but not Inline Feeder for folks like me.

 

[mknauss]

P.S. you also may want to consider updating the account settings when it asks for chlorine since there’s only two options to choose from Liquid or SWG but not Inline Feeder for folks like me.

That is on purpose. Those are the only two ways to chlorinate a pool on a daily basis following TFPC.

 

[cowboycasey]

ahhh, that is an easy one.. keep it there.. if you go with adding LC or a SWG.. you can still use pucks to raise CYA and for going on vacation... we are not against the use of them, you just can not live on them 24/7, your pool will get fat from CYA

As for SWG, grab a Circupool 45k or 60k, the 60k being better for you as you can run your pump about 10 hours or so instead of 14 or so with the 45k..

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[caseyrichards]

Ok guys. I’m convinced and happy to start running it 24/7. However I don’t have 1200 as an option. Closest is 1350 or 1100. And when I bump it down to 1350 the PSI gauge drops from 15 to practically 0 while the flow meter drops from 65 gpm to 30 gpm. Thoughts to dial it in?