Jandy Aquapure PLC1400 End of Life or Can I Make it Last Longer?

[wakerider017]

I have a 20K gallon salt water pool in Tampa, FL that is about 4.5 years old (original PLC1400). Recently I noticed some iron staining in the pool, so I brought FC down to 0.0ppm, pH down to 7.2ish and on 8/26/2023 added about 3lbs of ascorbic acid and added 2 quarts of Jack's Purple Magic. The pool did get a little cloudy and smelled a little 'off', but no algae growth. I let that sit for around 48 hours, backwashed DE filter and then turned my salt cell back to 90% running 9hrs a day (each year it seems I have had to ramp up these runtime percentages, especially in summers months). Also added some CYA to bring me to ~65ppm. CC was pretty high initially, (can't remember exactly but I think 3-4ppm, when the highest I've ever had before is 0.5ppm) and FC was low at 0.5ppm. More than 2 weeks later I am still only at 0.5ppm FC and 0.5ppm CC, so yesterday I took the salt cell off and did an acid wash. There was a little scaling in there, so I was hopeful that would make things right.

Now 24hours later (running the pump and cell overnight) I have 0.5ppm FC and 0.0ppm CC in my pool. My salt cell says it is supposed to put out 1.25lbs (20oz) per 24 hours at 100%. If I ran for 24 hours at 90% that should have been 18oz and in a 20K gallon pool +6.75ppm chlorine - which I am obviously not seeing.

I did test water coming directly out of the jet and that came in at 2.0ppm FC, so that tells me the generator is making some chlorine, but not sure if that is a significant enough amount?

Do you think the ascorbic acid and/or any left over organics are still eating up my chlorine (especially if my salt cell is on its last leg)?

I saw online you could hookup a dummy salt cell in your plumbing so you could look for bubbles in your actual unit while it is plugged in, but disconnected from the plumbing. I don't have access to any dummy unit so I can't do this, but is there anything I should try testing with my multimeter?

I should say my pool is crystal clear with no algae, so other than the testing be off - there is no observable problem...

 

[ajw22]

Does your pool pass a Overnight Chlorine Loss Test?

Your chlorine demand will increase as the chlorine clears the Ascorbic Acid from the water for a while.

SWG cells are usually binary. They give close to full output until they fail and don't give any output. Output does not taper off as it wears out.

Your SWG is probably working and you have higher FC demand from the AA and maybe some algae.

 

[wakerider017]

Does your pool pass a Overnight Chlorine Loss Test?

Your chlorine demand will increase as the chlorine clears the Ascorbic Acid from the water for a while.

SWG cells are usually binary. They give close to full output until they fail and don't give any output. Output does not taper off as it wears out.

Your SWG is probably working and you have higher FC demand from the AA and maybe some algae.

I have not done the OCLT, but that also says I need FC to be at or above 3.0ppm (which I have not been able to achieve).

That is really interesting that you say salt cells are binary... because I have had to gradually increase my percentages each year. Year 1, I could have the SWG at 60% mid summer and probably have FC at 8.0ppm with 60ppm CYA. Even before the ascorbic acid treatment I was at 90% this summer just to get 3-4ppm FC at CYA levels of 50-60.

I have NEVER slammed/shocked my pool before. I've never had any significant visible algae growth, so I guess I assumed it was not required. I wonder if that could be my issue?? I guess I should try slamming? That would be awesome if I could get some more time out of my salt cell.

 

[ajw22]

I have not done the OCLT, but that also says I need FC to be at or above 3.0ppm (which I have not been able to achieve).

Use Liquid chlorine. Add enough liquid chlorine to raise your FC around 8 ppm. Test your FC level 30 minutes after adding it.

How many gallons in your pool?

You using PoolMath ?

That is really interesting that you say salt cells are binary... because I have had to gradually increase my percentages each year. Year 1, I could have the SWG at 60% mid summer and probably have FC at 8.0ppm with 60ppm CYA. Even before the ascorbic acid treatment I was at 90% this summer just to get 3-4ppm FC at CYA levels of 50-60.

I have NEVER slammed/shocked my pool before. I've never had any significant visible algae growth, so I guess I assumed it was not required. I wonder if that could be my issue?? I guess I should try slamming? That would be awesome if I could get some more time out of my salt cell.

Algae can be invisible before it gets dense enough to be visible and the invisible algae can be consuming your FC.

 

[wakerider017]

20K gallon pool. I use PoolMath and have a TF100 test kit. Sounds like I'll need 1.5 gallons of 10% bleach to go from 0.5 to 8.0. Will try a local pool store since earlier this week Sam's Club and Walmart had ZERO bleach inventory.

If I fail my OCLT, I am thinking I will want to raise FC to 24 at CYA levels of 60? And for how long do I hold there?

 

[ajw22]

20K gallon pool. I use PoolMath and have a TF100 test kit. Sounds like I'll need 1.5 gallons of 10% bleach to go from 0.5 to 8.0.

Correct.

Will try a local pool store since earlier this week Sam's Club and Walmart had ZERO bleach inventory.

Walmart has stopped stocking Liquid Chlorine for the season.

If I fail my OCLT, I am thinking I will want to raise FC to 24 at CYA levels of 60?

Correct.

And for how long do I hold there?

For as long as it takes to satisfy the three exit criteria...

You are done when:​

• CC is 0.5 or lower
• AND you pass an OCLT (i.e. overnight FC loss test shows a loss of 1.0 ppm or less)
• AND pool water is crystal clear with no visible sign of algae (dead or alive) on floor and walls

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels.

 

[wakerider017]

@ajw22 you have been extremely helpful!! I am really hoping this will be the remedy for my pool and will allow me to run my SWG at lower percentages.

In the ascorbic acid info it says, "Do not raise to SLAM FC levels! Do not do a SLAM for at least 2 weeks!", Ascorbic Acid Treatment - Further Reading. I've been a little over 2 weeks now, but wondering if I should give it a few more days before slamming?

 

[HermanTX]

20K gallon pool. I use PoolMath and have a TF100 test kit. Sounds like I'll need 1.5 gallons of 10% bleach to go from 0.5 to 8.0. Will try a local pool store since earlier this week Sam's Club and Walmart had ZERO bleach inventory.

If I fail my OCLT, I am thinking I will want to raise FC to 24 at CYA levels of 60? And for how long do I hold there?

Since you live in FL, go to Pinch a Penny pool store to purchase LC. They normally stock it year round. They sell it in 2.5 gal jugs.

 

[ajw22]

@ajw22 you have been extremely helpful!! I am really hoping this will be the remedy for my pool and will allow me to run my SWG at lower percentages.

In the ascorbic acid info it says, "Do not raise to SLAM FC levels! Do not do a SLAM for at least 2 weeks!", Ascorbic Acid Treatment - Further Reading. I've been a little over 2 weeks now, but wondering if I should give it a few more days before slamming?

Start with the Overnight Chlorine Loss Test and see what your overnight FC loss is. It is a good benchmark to know.

Then if you fail get on with the SLAM Process. A few days is not going to make a difference.

 

[wakerider017]

I just had some time to get around to this and failed my OCLT this morning... Went from 4.5 FC last night to 1.5 FC this morning (pump running and salt cell off). I just would have never thought I had a problem because the water is perfectly clear.

I am a little frustrated at myself because I have the CYA so high (measurement just came in at 70 this morning) from earlier additions of stabilizer thinking that would help me keep my FC levels up... Now I have to SLAM with excessive amounts of CL. Oh well, at least liquid chlorine is not too expensive. Around $9 per 2.5 gallons at Pinch a Penny.

 

[JamesW]

but is there anything I should try testing with my multimeter?

Check the voltage and current.

Aquapure 1400 121 Error

I got the 121 error on my FusionSoft a couple days ago. I cleaned the cell and the sensor and the cell ran fine for about a day. Not this morning, it is back. It is still producing chlorine I can see bubbles out of the returns and the display also says it is on. I think my salt may be a little...

www.troublefreepool.com

 

[wakerider017]

This is super helpful!! Shows the proper volts/amps and how to test. Thanks!!!

Check the voltage and current.

Aquapure 1400 121 Error

I got the 121 error on my FusionSoft a couple days ago. I cleaned the cell and the sensor and the cell ran fine for about a day. Not this morning, it is back. It is still producing chlorine I can see bubbles out of the returns and the display also says it is on. I think my salt may be a little...

www.troublefreepool.com

 

[wakerider017]

Update on the SLAM... I am thinking my water must have been in worse shape than I thought. I used the rest of my liquid CL to bring up my FC to 21 at 9AM (confirmed level by testing). Had a late lunch around 2PM and picked up 5 more gallons of CL. Dumped in another 2G at 2:30PM to bring my FC level to 31 (did not test to confirm). Tested at 8PM and shockingly I was at 15.5FC 0.5CC and thats with the salt cell running at 80% all day!!

So I just dumped my remaining 3G of CL in. Turned the pump on to run overnight and turned the salt cell off. Will test actual FC levels in 30 mins so I can do my OCLT again in the AM.

I'm guessing I'm off to Pinch a Penny again in the morning to buy more CL. Might buy a 3rd jug...

 

[ajw22]

No point in doing a OCLT until your FC usage drops to less then 4ppm in a day.

 

[wakerider017]

No point in doing a OCLT until your FC usage drops to less then 4ppm in a day.

Any guidance on how long I may have to continue this? A few days? A week? Longer?

I tested last night and had 29.5FC. 18.5FC this morning.

 

[ajw22]

Longer then a week.

 

[JamesW]

Do you think the ascorbic acid and/or any left over organics are still eating up my chlorine (especially if my salt cell is on its last leg)?

As the ascorbic acid neutralizes the chlorine, the reaction can produce more hydrogen ions.

One gram of ascorbic acid will neutralize 1 milligram per liter of chlorine per 100 gallons of water.

2C5H5O5CH2OH + HOCL + OCl → 2C5H3O5CH2OH + H + 2Cl + 2H2O

Ascorbic acid + Hypochlorous acid + hypochlorite → Dehydroascorbic acid + Hydrogen ion + chloride + water.

The Dehydroascorbic acid probably breaks down over time as the carbon gets oxidized.

2C6H6O6 + 6H2O + 9OCl + 9HOCl --> 12HCO3 + 21H + 18Cl.

2C6H5O6 + 9OCl +9HOCl --> 12CO2 + 6H2O + 7H.

So, the reaction with chlorine produces another 0.5 moles of hydrogen ions per mole of ascorbic acid and the breakdown of the Dehydroascorbic acid produces another 3.5 moles of hydrogen ions per mole of ascorbic acid for a total of 5 moles of hydrogen ions per mole of ascorbic acid added.

So, the long term effect of adding 1 pound of ascorbic acid to 18,000 gallons of water should be a 9.5 ppm reduction in the TA.

C6H8O6 + 5OCl + 5HOCl --> 6CO2 + 4H2O + 5H + 10Cl.


The ascorbic acid loses one hydrogen ion (deprotonates) when the ascorbic acid is added to water and that lowers the pH and TA.

That converts the ascorbic acid to ascorbate.

C₆H₈O₆ --> C₆H₇O₆^- + H⁺

So, 1 lb. of ascorbic acid = 8.71 oz 31.45% (20º Baumé) hydrochloric acid for this part or 1.9 ppm reduction in TA for 18,000 gallons.

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The ascorbate reacts with chlorine and this produces another 0.5 moles of hydrogen ions per mole of ascorbic acid added.

So, 1 lb. of ascorbic acid = 4.355 oz 31.45% (20º Baumé) hydrochloric acid for this part or 0.95 ppm reduction in TA for 18,000 gallons.

2C₆H₇O₆^- + HOCL + OCl^- → 2C₆H₅O₆^- + H⁺ + 2Cl^- + 2H₂O

_____________________________________________________________________________________________________________________________

The dehydroascorbate reacts with chlorine and this produces another 3.5 moles of hydrogen ions per mole of ascorbic acid added.

The dehydroascorbic acid (dehydroascorbate) breaks down over time as the carbon gets oxidized and this produces more acid and it uses up more chlorine.

So, 1 lb. of ascorbic acid = 30.485 oz 31.45% (20º Baumé) hydrochloric acid for this part or 6.65 ppm reduction in TA for 18,000 gallons.

2C₆H₅O₆^- + 9HOCL + 9OCl^- → 12CO₂ + 6H₂O + 7H⁺ +18Cl^-

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The total reaction can be written like this.

C₆H₈O₆ + 5HOCL + 5OCl^- → 6CO₂ + 4H₂O + 5H⁺ + 10Cl^-

So, 1 lb. of ascorbic acid = 43.55 oz 31.45% (20º Baumé) hydrochloric acid for this part or 9.5 ppm reduction in TA for 18,000 gallons.


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So 3lbs of Ascorbic Acid would drop TA by 28.5 ppm? @JamesW

That is the total drop with the breakdown of the dehydroascorbic acid, but we do not know how long that takes.

The initial drop is 2.85 ppm per pound or 8.55 ppm for three pounds immediately (Acidity + Chlorine Reaction).

The breakdown reduces the TA by 6.65 ppm per pound or 19.95 ppm for three pounds.

The total reduction in TA should be 28.5 ppm for 3 pounds of ascorbic acid added to 18,000 gallons of water.

Some people report that they cannot get the chlorine level back up after an ascorbic acid treatment and this might be due to the reaction with the dehydroascorbic acid.

If you do another treatment, record the results and report them to see it the results match the calculations.

If the dehydroascorbic acid breaks down quickly, then the TA should drop and the FC will be harder to maintain.

However, if the dehydroascorbic acid takes a long time to break down, then the effect will be gradual and less noticeable.

At this point, I do not know if the dehydroascorbic acid breaks down in hours, days, weeks, months or years.

So, to simplify the answer somewhat, expect a TA drop of about 10 ppm immediately and another 20 ppm "eventually" if you add 3 pounds of ascorbic acid to an 18,000 gallon pool.

If the pH and TA drop as you begin to bring the FC back to normal after the treatment, then the dehydroascorbic acid is probably breaking down especially if the FC does not seem to be coming back as quickly expected.

Dehydroascorbic acid spontaneously decomposes to 2,3-ketogulonate and then to threonic acid and oxalate.

Oxalic acid/oxalate gets further oxidized to carbon dioxide.

HOCl + HC₂O₄^- --> H₂O + 2CO₂ + Cl^-

Oxalic acid can also remove rust stains.

Fe₂O₃ + 3H₂C₂O₄ --> Fe₂ (C₂O₄)₃ + 3H₂O

Iron Oxide (Rust) + Oxalic Acid = Iron(III) Oxalate + Water

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Effects of adding Ascorbic Acid?

@Leebo I know that Ascorbic Acid affects PH/Alkalinity, but I'm never sure how much it lowers PH/Alk, Can this be added to the PoolMath app?

www.troublefreepool.com

 

[kellyfair]

I am also in Tampa!

I keep 4 of the refillable jugs from Pinch a Penny. I don’t always have all of them full, but when my old SWCG died and before I installed my new one, it was good to have a big supply. Also, I sometimes use a little liquid chlorine to compensate for heavy pool use, rather than turning up the SWCG.

When you SLAM, turn off your salt cell. Easier to be precise with LC and why use up more of your cell’s life during a SLAM?

Lastly, try to avoid cleaning salt cell in acid, unless you absolutely must. Acid lowers the life of the cell by dissolving the coating on the plates that make the cell work. With my old cell, I think I cleaned it twice in the years I had it, and I used vinegar solution rather than acid.

 

[wakerider017]

@JamesW that is a bit above my head... I've already got 15 gallons of liquid chlorine added since Friday afternoon. Is that enough to eat up the approx 3lbs of ascorbic acid I added around 3 weeks ago now? The ascorbic acid changes into dehydroascorbic and eats more chlorine?? Ugh...

Kind of regretting adding the ascorbic acid. Really hoping I can ease off adding all this chlorine soon. Maintaining around 31ppm FC (5 gallons a day dumped in) is going to get expensive...

 

[JamesW]

You might have gotten some algae.

Is the cell running at 100%?

Can you check the amperage going to the cell?