SWG Chlorine generation demand increased dramatically after AA metal removal process

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G

gpatounakis

0
Oct 31, 2016
9
Longwood, FL
Dear TFP SWG forum,

I recently (about 2 weeks ago) treated my pool with AA (Leslie's Stain Remover) with MetalFree for the sequestrant. The stains were completely removed from the pool surface and everything seemed great. According to the instructions, I increased my FC by about 1ppm daily till getting to an FC of 5 (CYA about 75-80). This required my SWG to be set to about 80% output. After getting the FC to 5, I returned the SWG to the setting I had before the AA treatment that kept the FC levels in the pool stable, which was an SWG output of 9%.

After leaving it at 9% for a few days, the FC levels dropped dramatically. The weather around here hasn't changed much, so I cannot attribute it to the sun. Also, the combined chlorine level has been 0 all the time, so I don't think anything else is eating up the chlorine. I checked my pool's salt level at both the SWG which gave a reading of 3000ppm and with my Taylor kit which gave a reading of 3200ppm. The voltage across the cell and the amps are all well within the specs in the manual. I took out the cell and inspected it too. No buildup on the surface of the plates.

Is this because of the phosphate from the Metal Free I am using? Will switching to Jack "Purple" stuff fix this problem or is there something else going on?

Thanks!

-George
 
Welcome to TFP!

What is the water temp? And how much has it dropped in the last couple of weeks? The phosphates should have no impact on it and we don't even recommend testing phosphates. If your water is still above 60 then my first suspicion would be a little algae bloom.
 
Ascorbic acid is a chlorine neutralizer.

When you do the treatment, it's generally a good idea to use a dose of poly 60 algaecide to prevent algae during the time of zero chlorine.

As noted, you likely have the beginning of an algae bloom. Most algae does not create CCs.

If you Slam, you're likely to precipitate the metal again.

I would suggest that you add a dose of poly 60 and maintain fc at 10% of cya for 1 week by adjusting the swg as needed and running the pump continuously.

I would also recommend that you backwash the filter or break it down and give it a complete cleaning.
 
Thank you for the response!

The water temp currently is about 71 degrees F. During the AA treatment it was about 65F or so. I did the treatment during the week that the air temperature dropped to the 50's here thinking that I would have less trouble with algae. It has been getting a bit warmer these past few days (air temp in the mid to high 70's).

Also, I forgot to mention that my filter has been increasing pressure quite a bit faster than usual. From what I read on the site, that also may point to a algae problem.

-George

- - - Updated - - -

JamesW said:
Ascorbic acid is a chlorine neutralizer.

When you do the treatment, it's generally a good idea to use a dose of poly 60 algaecide to prevent algae during the time of zero chlorine.

As noted, you likely have the beginning of an algae bloom. Most algae does not create CCs.

If you Slam, you're likely to precipitate the metal again.

I would suggest that you add a dose of poly 60 and maintain fc at 10% of cya for 1 week by adjusting the swg as needed and running the pump continuously.

I would also recommend that you backwash the filter or break it down and give it a complete cleaning.
Click to expand...

Thank you for the reply and way to solve my algae problem. I will make a trip to Leslie's pool store and get a bottle of poly 60.

I was also planning to break down the filter this weekend anyway since I have no clue when it was done last since I bought the house recently.

-George
 
JamesW said:
Note that you can Slam if you have to. But be aware that the metal might restain. Hopefully, you can get it under control without a Slam.
Click to expand...

I just turned on the pump to run overnight and will go to the pool store in the morning to get the poly 60. The filter will be broken down and cleaned this Saturday. After that I will continue to run the pump around the clock and target my FC to about 8 given my CYA of around 80.

How will I know if it worked?

-George
 
Just checking to see why we're assuming algae here...post AA treatments chronically eat chlorine, and are entirely dependent on volume of AA used...and slamming WILL erode the effect of the sequestrant for sure and quite possibly the treatment overall.

Filter pressure can rise when using a sequestrant because it is binding the metal, and sometimes calcium also, and same is in filter.

On top of that, Metal Free is comprised of citic acid, which also acts like AA. In answer to your other question, yes, switch to jack's purple for SWG...Metal Free seems to produce unpredictable results and behaviors given many other threads I've read on the topic. Phosphonic acid is the more reliable sequestrant, and Jacks purple is formulated to prevent swg scaling.

I honestly would just increase the FC production for a few more days, and track consumption rate, which I predict should drop. If it doesn't drop in another week, do an OCLT and consider a slam but know you may then be starting over on the metal treatment.
 
I thought possible algae because it had been about a week later when the FC started dropping and it had held steady to that point. I'm not against your idea though.
 

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Maybe I misread, but when the swg was turned up to compensate until it got to 5 it was fine, but adjusted 9% it dropped dramatically...while that could indeed indicate early warning for algae, it can also reflect the decreased depletion from not only the AA, but the Metal Free, the MDS of which cites citric acid. This is why on metal threads I suggest fols use something other than Metal Free...eg a true phosphonic acid based sequestrant ;)

Hope that makes sense of my reasoning.

Which is not to say OP shouldn't be watchful for algae...and either way vigilant maintainance of FC to spec [fc/cya][/FC/cya] will be beneficial. Its just than slamming without positive proof of algae risks undoing the metal treatment.

OP...this is a balance of risk. Please track daily FC consumption...if there's a steady decline once you've dosed to spec (might be easier to do with bleach) from day to day, then it was likely the AA/Citric Acid effect...if theres a steady increase of consumption, might suspect nascent algae....to AI delta more evident, you might need to consider dosing with bleach instead of using swg for the moment to make results more clear cut.
 
I don't think that metal free is citric acid. The msds cites citric acid, but I think that it's a mistake.

Metal free has always been edta based. Maybe they changed the formula, but I don't think so.

Other msds sheets show edta with no mention of citric acid.

Stain free is citric acid. I suspect that they accidentally posted the stain free information on the msds.
 
Swampwoman said:
Maybe I misread, but when the swg was turned up to compensate until it got to 5 it was fine, but adjusted 9% it dropped dramatically...while that could indeed indicate early warning for algae, it can also reflect the decreased depletion from not only the AA, but the Metal Free, the MDS of which cites citric acid. This is why on metal threads I suggest fols use something other than Metal Free...eg a true phosphonic acid based sequestrant ;)

Hope that makes sense of my reasoning.

Which is not to say OP shouldn't be watchful for algae...and either way vigilant maintainance of FC to spec [fc/cya][/fc/cya] will be beneficial. Its just than slamming without positive proof of algae risks undoing the metal treatment.

OP...this is a balance of risk. Please track daily FC consumption...if there's a steady decline once you've dosed to spec (might be easier to do with bleach) from day to day, then it was likely the AA/Citric Acid effect...if theres a steady increase of consumption, might suspect nascent algae....to AI delta more evident, you might need to consider dosing with bleach instead of using swg for the moment to make results more clear cut.
Click to expand...

Oh OK. Initially, I found the FC hard to raise, which is what I attributed to the extra AA I used. I used a bit more AA than what the bottle since there would have been not even a 1/3 of the bottle left if I dosed exactly for 13,000 gallons. Maybe that was mistake #1 for me. My thought process was once the FC started to increase, that meant that all the extra AA got chewed up and the pool should be back to normal. I had no idea that the MetalFree would potentially make this a perpetual problem. I will order the "Purple Stuff" to use instead to see if that helps also.

As of right now, my FC is up to 7.5 (CYA is about 80). I put Polyquat 60 in the pool this morning (about 16 ounces for the 13,000 gallons). I brought my pH down to roughly 7.4 in the morning. Should I just hold it steady or turn my pump off for the night and see what happens in the morning to the FC?

Now another question that I have not have happen before - my pH reading tonight is odd. The solution is turning purplish (Taylor K2006 kit). I have had much higher FCs in my pool than 7.5ppm and have not had a problem with reading the test. Does the polyquat 60 used with the "initial" dose change the pH or interfere with the testing dye?

thank you everyone for pitching in to help me figure out my problem.

-George
 
Recently, chemical manufacturers had to update their MSDS forms to a new standardized format. The new sheets are called SDS. I think that when Natural Chemistry updated their sheets, they put the wrong information. Note that the new sheets are labeled “SAFETY DATA SHEET”, whereas the older forms said “MATERIAL SAFETY DATA SHEET”. The new sheets say citric acid whereas the older sheets say EDTA.

I do think that EDTA is the correct chemical. However, it's also possible that they changed the formula.

http://www.chemquip.com/customer/chquin/images/msds/naturalchemistry/NC_SpaMetalFree.pdf

http://www.appatek.com/MSDS/NATURAL%20CHEMISTRY%20POOL/Metal%20Free.pdf

Polyquat won’t affect the pH test.

In any case, I agree that switching to a phosphonic acid based sequestrant should help. Avoiding a Slam is the preferred way to go.
 
pooldv said:
FC at 10 or lower won't interfere with the pH test. I would expect the pH to drop with AA treatment, not rise. What is your TA?
Click to expand...

The pH rose after adding the Polyquat 60 this morning despite lowering the pH to 7.4 with 16 oz of Muriatic Acid (drop test is how I generally dose my acid which seems to have been working quite well for me over the last few months). TA was 70 yesterday. My TA always stays between 70-80 without the need for adding anything.
 
That makes a lots of sense, James...the SDS I've been referring to since at least last season is on their own website here: https://media.nat.cm/filer_public/73/3a/733ae588-bfea-4353-b5af-aa960d345950/metal_free_-_english_sds_-_jul14.pdf and indeed lists only citric acid, which makes no sense to me whatsoever ;)

In the interest of accuracy, I should try to call them and sort this out. There were a couple of threads this summer reporting an apparent lack of efficacy in sequestration where it was being used, as well as ad hoc reports of high chlorine demand, etc. so just assumed they'd found an occasion to further bottle citric for profit, as counter-intuitive as it seemed ;)

I know less about EDTAs behavior than phosphonic acid, save that even Jack's tech admits their EDTA product (jacks magenta) is "less aggressive" in sequestering metal, iron in particular, but really good at picking up plaster dust and excess calcium etc.

I also know that Jacks Magenta is known to interact with polyquat 60....SO if Metal Free is EDTA, do you think it will cloud the OP's pool?
Or is it perhaps another ingredient that causes the magenta-poly60 reaction?

GPA - sorry if this is seeming a bit "in the weeds" here, but the interactions of different types of metal products can get complex and there's not a boatload of transparency in the mfg industry since parts of their formulations are proprietary.

This is one of the reasons why in general TFP most advocates use of the simplest elements for pool care (eg bleach) and is generally wary of "special formulations" from the pool industry... ;) (First do no harm, as they say ;) Of course, this isn't always possible when dealing with metals...but the equivalent approach would be pure ascorbic acid (not branded or mitigated) with a known phosphonic acid such as Metal Magic or Jack's (but not magenta) in terms of increasing the odds for predictable results.

So regarding the crazy purple reading...check again tomorrow and see if it has settled down. I realize you're getting a lot of "wait and see" from me but sometimes that's better than tinkering ;) And trust me, those are words from a notorious tinkerer ;)
 
Swampwoman said:
That makes a lots of sense, James...the SDS I've been referring to since at least last season is on their own website here: https://media.nat.cm/filer_public/7...0d345950/metal_free_-_english_sds_-_jul14.pdf and indeed lists only citric acid, which makes no sense to me whatsoever ;)

In the interest of accuracy, I should try to call them and sort this out. There were a couple of threads this summer reporting an apparent lack of efficacy in sequestration where it was being used, as well as ad hoc reports of high chlorine demand, etc. so just assumed they'd found an occasion to further bottle citric for profit, as counter-intuitive as it seemed ;)

I know less about EDTAs behavior than phosphonic acid, save that even Jack's tech admits their EDTA product (jacks magenta) is "less aggressive" in sequestering metal, iron in particular, but really good at picking up plaster dust and excess calcium etc.

I also know that Jacks Magenta is known to interact with polyquat 60....SO if Metal Free is EDTA, do you think it will cloud the OP's pool?
Or is it perhaps another ingredient that causes the magenta-poly60 reaction?

GPA - sorry if this is seeming a bit "in the weeds" here, but the interactions of different types of metal products can get complex and there's not a boatload of transparency in the mfg industry since parts of their formulations are proprietary.

This is one of the reasons why in general TFP most advocates use of the simplest elements for pool care (eg bleach) and is generally wary of "special formulations" from the pool industry... ;) (First do no harm, as they say ;) Of course, this isn't always possible when dealing with metals...but the equivalent approach would be pure ascorbic acid (not branded or mitigated) with a known phosphonic acid such as Metal Magic or Jack's (but not magenta) in terms of increasing the odds for predictable results.

So regarding the crazy purple reading...check again tomorrow and see if it has settled down. I realize you're getting a lot of "wait and see" from me but sometimes that's better than tinkering ;) And trust me, those are words from a notorious tinkerer ;)
Click to expand...

That is my general approach to many things in life -- less is more. :)

I will leave the pump and SWG running overnight and recheck readings in the morning. I don't like the idea of using MA in the dark for safety reasons anyway.

Thanks again for the guidance!

-George
 

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