FYI - Surprising Sources Of Metal In Pool Water Identified And Fixed (Update)

ChuckDavis

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Aug 6, 2010
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Durham, NC
In 2014 I documented some unusual sources of metal staining. (See below.)

I have subsequently discovered that in autumn, leaves falling into the water from some of the trees around our pool can also cause metal staining. Jack's confirmed that leaves can be a metal source. I am able to control or lift the stains using Jack's Magic Blue Stuff during the period that leaves are falling into the pool.

Original June 2014 Posting:

It's been a years long process, but I think I have finally identified the remaining sources of metals in my water. Up until this year I have been dealing with metal stains and have had to do one or two ascorbic acid treatments each year. This year there have been no metals and no stains. Hopefully this information might help somebody else.

Several years ago we had our pool refurbished, including a poured concrete coping. The concrete was colored brown, and the contractor put a brown powder on the wet concrete before stamping the pattern. Once the concrete dried they put on a coat of clear sealer. Looking back, however, they were rushing when applying the sealer due to the threat of rain.

Last fall I was talking with tech support at CuLator, and the support tech mentioned that he had encountered metals leaching out of colored concrete copings. I confirmed that the concrete colorant and colored powder do contain metals. I applied a coat of sealer last fall, and I think that this is the biggest reason that I have been metal free.

I have since learned that it is best practice to put on a new coat of sealer each year, and that it is important to match the type or brand of sealer year to year.

The other probable source of metal was the chrome trim ring on my Pentair Amerlite pool light.

I replaced the trim ring several years ago, but within a year the ring had turned a tarnished black. I checked my bonding wires, but everything seemed fine. I put a zinc on the light, but the zinc dissolved within a year.

This spring during my travels around the Internet I discovered that the replacement screw from Pentair for fastening the trim ring to the niche was brass. The screw that I had was stainless steel. Pentair tech support couldn't explain the change, but did confirm that they now recommended using the brass screw. A quick web search showed that stainless steel has a much higher resistance to electrical current than brass. I am assuming that the high resistance of the stainless steel screw was causing galvanic corrosion between the trim ring and the (bonded) niche, resulting in metal being deposited into the water.

I purchased a new trim ring, which came with a brass screw. So far it is bright and shiny.

I hope this information is useful to somebody.
 

kimkats

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WOW what a journey you have been on trying to figure this all out! Thanks for the write up! I hope this can help someone in the future!

Kim:kim:
 

ChuckDavis

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Durham, NC
In case you end up coaching somebody else on metals and sequestrants, this information might also be useful. The fact that filter media has to be able to filter particles 10 microns or less in size in order to remove sequestered metal is important. A sand filter by itself won't work.

 
Last edited:

duraleigh

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The most common source of metal is from fill water taken from a well. You tested the fill, correct?
 

ChuckDavis

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Oh yes. Years ago. Phosphates, but no metals from Durham, NC tap water. (I am on the "ignore phosphates and trust chlorine" side of that theological argument.)

The demonstrated success of (re)sealing the coping, replacing the trim ring (and screw) and using sequestrant in fall would seem to validate what worked for me. If somebody else has unexplained metal(s), and has dealt with all the "usual suspects", hopefully my experiences might give them some other ideas to consider.
 

duraleigh

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That's a good write up about unexpected metal sources. I would not have guessed either the trim ring or the coping would have released enough metal to cause staining but that sure looks like what happened.

My assumption is that since the ascorbic acid cleared the stains that iron was the culprit. I don't think that trim ring has any iron in it so I am wondering if that "coating" was the sole source........just guessing, I don't know.
 

borjis

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Aug 19, 2014
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Pacific NW
I'm on municipal water but found recently on a water test report that some of the water sources
do have metals. Not much, but enough that every other year, when I add the first chlorine the
water turns green. The last two times this happened I just replaced half the pool water which
got the green out. Last year it started to stain my liner a bit of a tan brownish color.

It shouldn't happen next spring, but if /when it does next, I plan to try the jack magic pink stuff.
Very likely to cost less or be equal to the inconvenience of partial draining / refilling.
 

ChuckDavis

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Durham, NC
I agree that the (unsealed) coping was the primary culprit (along with leaves in the fall), but the "chrome" from the trim ring did go somewhere. In (inevitable) hindsight, another symptom was brown stains on the tile grout under the coping.
 

ChuckDavis

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borjis - See my linked article above. With your sand filter you will need to use DE or fiber to get the sequestered metal out of the water after you use Jack's Stuff.
 

borjis

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Aug 19, 2014
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Really??
I thought that was only for Metal out and the Jack's was more of a temporary solution to the problem (green to blue water)
 

ChuckDavis

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Nope. Jack's Blue/Pink/Purple Stuff is HEDP sequestrant. It is "temporary" if you don't filter the sequestered metal out of the water and then backwash. The HEDP will eventually break down and release the metals back into the water.

 

borjis

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Aug 19, 2014
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Good to know. I bookmarked your well researched post.
Holy cow that was a TON of blue-stuff you used!

I'll probably try the layers of polyfill in the skimmer first if it does turn green. Then your methodology if that doesn't help.
Some have succesfully removed or heavily reduced their metallic water that way.

thanks!
 

ChuckDavis

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Tell me about it! Luckily I use Zeolite in my sand filter, so I don't have to use any DE or fiber.

I would be surprised if the polyfill captures the metal ions (unless it happens to have an opposite ionic charge). I think the metal ions need to be bound to the large sequestrant molecules in order to be mechanically filtered.
 

Demegrad9

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May 27, 2017
359
Coventry, CT
Leaves can cause metal stains? Maybe that explains my experience. Each year upon opening the pool the white fiberglass steps get leaves on them as the stairs stick out and just barely stay covered by the winter cover and the stairs tend to get stained reddish orange. Thinking it was an organic stain I tried a trichlor puck but it did nothing. Next was vitamin c and immediate improvement which indicates iron. This baffled me since I had my well water tested and iron was almost nonexistent and I never see staining anywhere else. Just those stairs and even that only gets stained over winter.

Could leaves have that much iron?
 

duraleigh

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Leaves easily cause organic stains (tannin) when they sink to the bottom of the pool but chlorine is the cure. I am not aware of leaves having any metal content.
 

ChuckDavis

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Durham, NC
My experience, confirmed by Tech Support at Jack's and my success using Jack's Magic Blue Stuff, is that leaves are the source of metal in my pool. Chlorine, even applied directly and full strength, won't touch the stains in the fall, but Jack's Magic Blue Stuff sequestrant lifts the stains (slowly) and prevents further staining until leaf fall has ended. I only have to use sequestrant during the fall.

There is, of course, some tannin from the leaves so I keep my chlorine a little higher in autumn as a preventative.
 

borjis

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Aug 19, 2014
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Pacific NW
I would be surprised if the polyfill captures the metal ions (unless it happens to have an opposite ionic charge). I think the metal ions need to be bound to the large sequestrant molecules in order to be mechanically filtered.
meant I would use the polyfill when it is green and out of solution / collectable.
 

borjis

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Aug 19, 2014
3,033
Pacific NW
Each year upon opening the pool the white fiberglass steps get leaves on them as the stairs stick out and just barely stay covered by the winter cover and the stairs tend to get stained reddish orange. Thinking it was an organic stain I tried a trichlor puck but it did nothing. Next was vitamin c and immediate improvement which indicates iron. This baffled me since I had my well water tested and iron was almost nonexistent and I never see staining anywhere else. Just those stairs and even that only gets stained over winter.
The "almost nonexistent" is my case as well. My water supply co recently showed on test results that 1 of their 3 water
sources has traces of iron, where the others have none at all. I've been getting that brownish / orange stain in my
skimmer since I bought the place in 2015.

I don't get any leaves in my pool at all, but I do get a ton of that pine straw from a neighbors tree.
We had a windstorm early today and I kid you not, I scooped out a 10 gallon yard debris bin's worth of
it before leaving for work today.
 

Demegrad9

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May 27, 2017
359
Coventry, CT
Whatever the cause I'm not going to worry much about it. Last season it took about an hour with a bunch of vitamin C tablets and couple magic erasers to get stairs clean!