SWG Flow and pump RPMs?

[Steve-D]

Pool equipment details are in my signature...

This is our first SWG pool so this is new to me. This morning while adding dry acid to bring down the PH a bit I was adjusting the pump speed and noticed that the SWG Flow LED goes to red (low/no flow) if I set the pump below 1650 RPMs. Is that to be expected? Is it an indicator that I should clean the filter if I want to facilitate Chlorine generation at a lower RPM setting or will that not affect the flow enough to make a difference? If I want to run the pump on low to keep filtration going without generating more Cl do I just slow the pump down until the Low/No Flow indictor goes red? Do folks with an SWG system paired with a variable speed pump usually try to run it a speeds which will add Cl to the pool?

My FC is currently at 8.0 with CYA at 60 so the level is at the high end of good, but it has been creeping upwards with the solar cover on all week, no swimming and little to no sun to break down the existing Cl. Having just added dry acid I need to keep the water circulating but I'd also like to keep the addition of new CL to a minimum.

 

[Jimrahbe]

Steve,

In my mind running the pump without generating chlorine just does not make sense. If you are generating too much FC, just reduce the cell output.

The IC40 will not make chlorine if the low flow light is on.

Each pool is different, but if you don't have a heater, you should be able to turn on the flow switch at 1100 to 1400 RPM. If you do have a heater, then you will most likely need to run 1500 to 1800 to turn on the flow switch inside the cell.

You should never use dry acid when you have a salt cell. You need to be using Muriatic Acid (MA). Dry acid can ruin the cell.

When was the last time you cleaned your filter? What is the clean filter pressure and what is it now?

When you stick your hand in front of the pool return, do you feel a good flow or is it weak?

Thanks,

Jim R.

 

[Homebrewale]

First, start using muriatic acid instead of dry acid to lower pH. There is sulfur in the dry acid that can shorten the life of your SWG cell.

Yes, I lower the speed on my VSP to find out when the SWG will shut off. Then run the VSP at 100-200 rpm above the shutoff value. I have found that there is difference when the SWG shuts off between clean and dirty condition inside my sand filter. My VSP is set for clean conditions. If the SWG LED goes to red for low/no flow, that is an indicator that I need to clean my filter.

 

[Steve-D]

Thank you both @Jimrahbe and @Homebrewale.

Flow feels OK for the speed the pump is going at (1750) but this is my first VSP and its a new pool so I don't have any past experience to judge it by. @ 1650 RPMs pressure reads 6, @ 3000 it reads 15. We have not yet cleaned the filter and it would be for the first time. We have a heater but it is not yet enabled. The last steps in this new build is programming the panel & getting the heater running and we are waiting for the installers to get a commitment from Pentair to come out and do that. My wife is not happy with the PM for our installation over this.

I have been using up left-over dry acid from the installers but I also have muriatic acid (20% Klean-Strip Green from Home Depot) so I will use that going forward...my brother in law can take what's left of the dry acid for his (vinyl/Cl/unheated) pool. I kept seeing that MA is recommended for SWG systems but this is the first time I've heard why...and I'm a big believer in understanding the "why" in most things.

The SWG is set at 2% so I'll see if adjusting it down gets it to 1% or if it just shuts it off. As a new pool we don't yet have a baseline for what to expect in needed FC production but that will come with time. Hopefully we'll see enough sun this weekend to keep the solar cover off and with that and enjoy some more usage (plus I need to skim and vacuum).

On a FC related question...I grabbed a small bucket of stabilized pucks and granulated Chlorine to get the pool balance started while we were waiting for adding salt and turning on the SWG. I still have a few gallons of the liquid (un-stabilized) Chlorine as well, all of which I was using while we were first trying to get the CYA level to a point where the Cl didn't just disappear the by the next day. The stabilized Cl is easier to store than the liquid without losing its potency...is there any value to keeping some of the stabilized Cl on hand? How likely is it that will I need to tweak the FC level by manually adding Cl such that keeping any or all of that around is worth it? Again, I can pass it along to my brother-in-law so it won't go to waste and there won't be a disposal issue.

[edit] I also have an unopened 4 lb bag of (Clorox) stabilizer so I do have a way of boosting the CYA if needed without using the stabilized Cl.

 

[ajw22]

There is sulfur in the dry acid that can shorten the life of your SWG cell.

Sulfates, not sulfur, in dry acid.

Sulfates is a salt or ester of sulfuric acid.

 

[ajw22]

We have not yet cleaned the filter and it would be for the first time. We have a heater but it is not yet enabled. The last steps in this new build is programming the panel getting the heater running and we are waiting for the installers to get a commitment from Pentair to come out and do that. My wife is not happy with the PM for our installation over this.

How long has your pool been open? Since water was added to it?

What heater do you have? I don't see it listed in your signature.

With a Pentair gas heater you probably need around 1750 RPM to get enough flow for your SWG and heater.

I'm a big believer in understanding the "why" in most things.

Acid - Further Reading

www.troublefreepool.com

On a FC related question...I grabbed a small bucket of stabilized pucks and granulated Chlorine to get the pool balance started while we were waiting for adding salt and turning on the SWG.

You can give them away or save them for when you go on vacation and put them in a floater in your pool.

I still have a few gallons of the liquid (un-stabilized) Chlorine as well, all of which I was using while we were first trying to get the CYA level to a point where the Cl didn't just disappear the by the next day.

Keep it in case you need to booost your FC.

Breakdown of Bleach Over Time by Storage Temp - Further Reading

www.troublefreepool.com

 

[Jimrahbe]

We have a heater but it is not yet enabled.

Steve,

As long as the heater is connected to your plumbing, it will cause a restriction to the water flow back to the pool. This means you will have to run your pump faster to make up for it.

Thanks,

Jim R.

 

[Homebrewale]

Sulfates, not sulfur, in dry acid.

Sulfates is a salt or ester of sulfuric acid.

Yes, sulfates is a sulfur compound. I didn't know I had to be that specific. I'm a chemical engineer so I do know the difference.

 

[ajw22]

Yes, sulfates is a sulfur compound. I didn't know I had to be that specific. I'm a chemical engineer so I do know the difference.

You say sulfur and some people expect the rotten egg smell to tell them if something has sulfur.

 

[Homebrewale]

You say sulfur and some people expect the rotten egg smell to tell them if something has sulfur.

That would be H2S.

 

[Steve-D]

Doh! I missed adding the heater to my signature ...was going off some awkward pics I took of the pool equipment. It is there now (Pentair Mastertemp 400 running on propane) and yeah, I get that its in the flow so whether its "enabled" or not it still affects the flow.

The pool was Opened" on 5/6 with waster added and the pump has been running slow and continuously since then apart from some brief shutoffs while the booster pump for the Polaris was inserted into the flow. According to our installer the pump PSI is not quite at where they would suggest cleaning the filter cartridges. I've been watching videos on the process but I'd prefer to clean it first time while they are here. The videos got me looking and I noticed that the filter is oriented so that the filter drain faces the heater (control panel side) and they are only separated by about 12-15 inches...that's going to be fun to manage.

 

[ajw22]

Do you know what your clean filter PSI was when the equipment was started?

We recommend you clean the filter when the PSI is 25% over the clean filter PSI.

Post pics of your equipment pad.

 

[Steve-D]

Here is the pad...
I don't recall the on startup psi, but I remember the installers saying to clean the filter at 20 psi.

Ugh...cleaned the solar cover as best we could without spilling all sorts of pollen and pine needles into the pool. Skimmed, set the Polaris cleaning and just tested.
Ph dropped as expected (7.6) and I added 25 oz 20%MA to bring it down a little more. TA is holding @ 100 but (unless I'm botching my readings) now FC per drop test is up to 12. I'll test again in a few hours to give the MA time to disperse before I do. We have some sun today so that should help,too, if that proves to be a true reading. My test kit and reagents are a year old...could that affect these readings?
With all the pollen & springtime debris I don't want to turn off the pump...is there a way to run it at a usefully rpm and disable the intellichlor so it isn't Dding more FC? It's already set at only 2% (flashing green).

 

[Jimrahbe]

Steve,

Set the IC40 to zero output.. That will shut the cell off.

Unless your pool is constantly covered, a SWCG output of 2% should not be raising your FC.

Thanks,

Jim R.

 

[ajw22]

Set the Intellichlor to its lowest %. It will give you almost no FC. Then be patient.

 

[Steve-D]

IC40 has been set @2% from the start. Pool was covered continously from Mon PM to Sat AM (today).The panel isn't programed yet so we don't have access to settings via the app. How do we set IC40 to 0 output from its own controls?

 

[Steve-D]

------------------------------------------
Notes 06-05-2022 @ 10:15 AM
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Water temp 72, cover off and the pool is just starting to get direct sunshine. Running the Polaris cleaner mostly just off the boost pump w pump @ 1500 rpm so slow flow/ no FC currently being produced.
FC down 0.5 from last night, PH down by 0.1 and TA up by 10 from yesterday AM. For TA it is the 1st change in weeks.

------------------------------------------
Test Results 06-05-2022 @ 10:00 AM
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Free Chlorine: 11.5
Combined Chlorine: 0.0
pH: 7.5
Total Alkalinity: 110

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Chemical Addition 06-04-2022 @ 01:15 PM
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+ 28 FluidOunces of MuriaticAcid20%

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Test Results 06-04-2022 @ 01:13 PM
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Free Chlorine: 12.0
pH: 7.6
Total Alkalinity: 100

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Chemical Addition 06-03-2022 @ 07:47 AM
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+ 20 Ounces of DryAcid

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Notes 06-03-2022 @ 07:24 AM
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water temperature 72

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Test Results 06-03-2022 @ 07:10 AM
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Free Chlorine: 8.0
Combined Chlorine: 0.0
pH: 7.8
Total Alkalinity: 100
Calcium Hardness: 240
CYA: 60

 

[Steve-D]

Sunny day running the pump with slow/ no flow for 0 FC production and FC is now down to 8.5. Cover is back on, running pump slow overnight to clear up pollen (from cover)...will check FC, PH and TA again in the AM.