Minimum RPM for salt cell

[crosby1612]

Is there a minimum pump speed for the flow sensor on a salt system? Pool company set my minimum pump speed at 1750 rpm and I notice sometimes I get a "no flow" reading on the control unit. Any thoughts on this?

 

[ajw22]

It all depends on your equipment and plumbing setup.

You need to experiment and discover what works for your setup.

Start high RPM and with a clean filter and lower your speed 100 RPM at a time until you get No Flow. Then add 200 RPM for when your filter gets dirty and that is probably a good minimum speed for your pool.

 

[mknauss]

What pump do you have? Please complete your signature with all the equipment you have.

 

[Jimrahbe]

Crosby,

Something else to check is that the cell's power center should not get any AC power when the pump is off.. If your system is not wired correctly then, when the pump turns off, you will get a no flow alert.

Thanks,

Jim R.

 

[crosby1612]

Crosby,

Something else to check is that the cell's power center should not get any AC power when the pump is off.. If your system is not wired correctly then, when the pump turns off, you will get a no flow alert.

Thanks,

Jim R.

Thanks. That isn't the issue.

 

[crosby1612]

What pump do you have? Please complete your signature with all the equipment you have.

This one: Jandy VSFloPro. VSFHP185DV2A

 

[mknauss]

Great. With a 1.85 hp VS pump, you will have to run at a higher rpm than those with 3 hp VS pumps.

 

[Dirk]

Thanks. That isn't the issue.

Jim wasn't addressing your original issue. He was giving you some advice about something else to check on to ensure your setup is safe. An SWG should have at least two safeguards: (1) a properly functioning flow switch to make sure that the cell doesn't try to generate when the pump is not producing enough (or any) flow through the cell, and (2) that when the pump programming shuts down the pump, that power to the cell is also shut down (no lights).

These are two different safeguards, and because of the potential danger of an SWG producing chlorine gas in your plumbing when no water is flowing through it, it's prudent to determine that you have both safeguards in place.

The second "power off" safeguard has nothing to do with your original question about optimum flow for your SWG.

 

[crosby1612]

Thanks. The pump has been running 24/7 @ 1750rpm since April. New pool, new pump, etc. This is a recent issue with "no flow". Filters are cleaned religiously, so I'm at a loss. Sensor gone bad maybe?

 

[Jimrahbe]

Filters are cleaned religiously,

Crosby,

What does that even mean??? With a VS pump running at 1750 and fairly large cartridge filter, you should only have to clean your filter once or twice a season.. I assume you close for the winter.

How often do you clean your filter now?? And, how long since the last time you cleaned it??

As a test, change your pump speed to 1800 or 1900 and see if the flow problem goes away.. If it does, then the sensor is working. If not, then I would look at the sensor..

Normally, when things are running fine at XXXX RPM and then the flow gets less and less, it is a sign of algae, even if you can't see it yet.

What is your normal filter pressure and what is it now with the SWCG not working??

Thanks,

Jim R.

 

[crosby1612]

Crosby,

What does that even mean??? With a VS pump running at 1750 and fairly large cartridge filter, you should only have to clean your filter once or twice a season.. I assume you close for the winter.

How often do you clean your filter now?? And, how long since the last time you cleaned it??

As a test, change your pump speed to 1800 or 1900 and see if the flow problem goes away.. If it does, then the sensor is working. If not, then I would look at the sensor..

Normally, when things are running fine at XXXX RPM and then the flow gets less and less, it is a sign of algae, even if you can't see it yet.

What is your normal filter pressure and what is it now with the

Crosby,

What does that even mean??? With a VS pump running at 1750 and fairly large cartridge filter, you should only have to clean your filter once or twice a season.. I assume you close for the winter.

How often do you clean your filter now?? And, how long since the last time you cleaned it??

As a test, change your pump speed to 1800 or 1900 and see if the flow problem goes away.. If it does, then the sensor is working. If not, then I would look at the sensor..

Normally, when things are running fine at XXXX RPM and then the flow gets less and less, it is a sign of algae, even if you can't see it yet.

What is your normal filter pressure and what is it now with the SWCG not working??

Thanks,

Jim R.

Why the multiple question marks? I'm trying to understand what the problem is with my salt system. Like I said, Jim, new pool, new system, new everything as of April. Has been working fine until the past few weeks when I'm getting a "no flow" error message the salt panel. The filters are cleaned when they need to be cleaned. Point being I take care of the system.

I never saw the "no flow" error until recently and the pump has been running 24/7 at 1750 rpm since April. Now I'm getting the "no flow" error at that speed.

I'm simply looking for an answer to the problem. Pool is chemically balanced, yet there's unseen algae? "What does that even mean?"

 

[Dirk]

I'm simply looking for an answer to the problem. Pool is chemically balanced, yet there's unseen algae? "What does that even mean?"

Please review Jim's last post and answer each question he asked you. He's troubleshooting with you, and his questions all make sense, even if not yet to you. Early symptoms of algae don't always include visual ones. Only proper testing can confirm or eliminate algae as a possibility. So yes, algae can be "unseen" and until we know about your testing methods, "chemically balanced" doesn't mean anything useful to the troubleshooting.

Please include in your signature the type of test kit(s) you are using to determine "Pool is chemically balanced." In order to give you the best advice, we accept test results from one of only two test kits. Are you testing yourself, or taking your water to a pool store for testing? Please post the following from a recent suite of tests, in this exact format:
FC =
CC =
pH =
TA =
CH =
CYA =

We can help you figure out what is going on, but we need you to provide test results and answers to troubleshooting questions.

The most likely culprit of your "low flow" symptom is a filter working less efficiently than it once did. It could be a faulty flow switch, but the filter is more likely. It actually makes perfect sense that your flow at 1750 worked fine until the filter accumulated some gunk, gunk that even cleaning would not fully remove. Your filter cartridges will never again pass water as well as they did when brand new (until you replace them), no matter how well or how often you clean them. If your builder happened to set your SWG to work well at it's minimum flow rate, then even a small amount of resistance in your filter would push the flow below the SWG's threshold. That gunk could be normal, or it could be algae. A higher flow rate might be what you have to use going forward, or you might get back to 1750 if it is, in fact, algae that can be eliminated.

If your flow rate is borderline for your SWG, even stuff in your skimmer or pump baskets can bring on a "low flow" condition. That's why we recommend you determine your SWG's minimum flow rate when everything is perfectly clean, and then add about 200 RPM to account for the inevitable accumulation of gunk in your baskets or cartridges.

Answers to Jim's questions, including test results, will help determine what if going on.

You should read up on the test kits we all use:

Swimming Pool Test Kits Compared

What pool test kit should I buy? Why shouldn't I use test strips? Our recommended test kits will pay for themselves in no time!

www.troublefreepool.com

 

[crosby1612]

Thanks.

The filter was cleaned 30 days after initial plaster and again about 3 weeks ago.

FC = 7
CC = 0
pH = 7.8
TA = 70
CH = 450
CYA = 60

I am using the TF Pro Salt test kit.

Filter pressure runs 5-10 and doesn't change with the "no flow" message on the salt panel.

Just for fun I took the filter apart again and this screen was completely covered with gunk. What is it and what is its function? Could that be the cause of the no flow error message on the salt panel?

 

[proavia]

That is the air bleed line to help purte any air at the top of the filter.
It won't affect filter presssure - clean or covered with debris.

If the flow light is on, increase pump speed by 100 rpm at a time until the flow light goes out.
Then increase the pump rpm 200 more rpm to account for the filter getting dirty over time.

Add your test kit to your signature.

https://www.troublefreepool.com/account/signature

Also, suggest you do an Overnight Chlorine Loss Test to rule out any issue with a nascent algae bloom.

 

[wireform]

To be honest 1750 was just good for a brand new system but please follow the advice given before me, them people are good at getting to the solution.

 

[Dirk]

To be honest 1750 was just good for a brand new system

Did you find that the 1750 worked while everything was new, but that you haven't been able to get back down to that speed, even after backwashing your filter?

That's my hypothesis for the OP. His builder happened to set the RPM at just barely above what the SWG needed, and just the "breaking in" of his cartridges, accumulating enough stuff that doesn't get cleaned out, has permanently altered the minimum RPM required for his SWG. The only way he might get back to 1750 is when he replaces his cartridges, but then those, too, will eventually clog up enough to require a higher RPM, too.

Every pool and its plumbing is different. Length of pipes, number of 90s, filter type, number of returns and skimmer, where the SWG is in the plumbing, etc. All those parameters affect the RPMs required to satisfy the SWG's minimum flow rate. Even each SWG has a slightly different requirement, based on how well the flow sensor works. The SWG will need what it needs, and other than keeping the SWG, filter and baskets clean, and the pool free of algae, there's not much else that can be done about that.

 

[crosby1612]

Yes, the 1750 rpm was working just fine until maybe 2 or 3 weeks ago then I started to get the "no flow" message. I called the pool company, they're actually scheduled to come out and replace the sensor (under warranty) but now I'm not so sure that's what it is. If I run the pump at a little higher speed it seems to be just fine. I also cleaned the cartridges again today, and now I'm not getting the error message at 1750. I don't really understand why people say you should only clean once or twice a year. It literally takes me about 20 min to take everything apart, clean, and put it all back together. 20 minutes of my time is well worth the effort to have a clean and efficient system.

I kind of don't want them replacing something that isn't broken.

Thanks for your insight; this makes the most sense to me about what the issue is.

 

[proavia]

Continue to lower the rpm by 100 rpm until the no flow light comes on. Then increase until the no flow light just goes off. Add 200 rpm to that number. That should allow a bit of head room for the filter getting dirty.

It is recommended to clean the filter when pressure rises 25% above clean pressure.

Unless you get a lot of dirt and debris in your filter, you shouldn't have to clean your 340 sq ft cartridge filter one or two times a year. Maybe mid season and end of season (at closing).

 

[Jimrahbe]

crosby,

My comment about only having to clean the filter once or twice a year was based on not having algae...

My pool is open 365 and is never closed, even in the winter.. I clean my filter once a year.. I used to do it twice a year, but found it made no difference in water flow. Then again, I don't have algae...

Thanks,

Jim R.

 

[crosby1612]

crosby,

My comment about only having to clean the filter once or twice a year was based on not having algae...

My pool is open 365 and is never closed, even in the winter.. I clean my filter once a year.. I used to do it twice a year, but found it made no difference in water flow. Then again, I don't have algae...

Thanks,

Jim R.

got it. thanks.