Recurring Metal Stains... worse than ever...

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carlos31820

carlos31820

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LifeTime Supporter
Nov 22, 2010
413
Midland, Georgia
I've posted in the past about our recurring metal staining issues. I'm at the end of my rope dealing with this frustrating issue. Before this season started, we had to repair a section of vinyl liner track that had come undone from the pool wall. I took the chance to do an AA treatment and drained all but the deep end of the pool. Even with all that water removal, my water stain problems this season are just as bad as they've ever been, maybe even worse.

I'm starting to think that my issue may be related to the salt chlorinating cell. I'm wondering if the chlorine level and pH levels inside the cell are enough to break down my metal sequestrant and/or make my metals drop out of solution. I have a floor cleaning system and it seems like the staining in concentrated on the areas where the wall jets and floor jets spray. My liner is completely stain free above the wall jets (they only spray down the wall).

I sent water samples to the makers of the CuLator product. They do professional water testing. You basically send them a sample of your pool water as well as a sample of your source (fill) water to make sure the source water is not the problem. Much to my dismay, their testing found no metals in my water. They sent me an email today after I emailed them a video showing that happens when I add GLB Metal Magnet to the pool stain. It's immediately removed.

This season, I'm only able to keep the stains at bay for about a week before I have to use a stain remover (GLB Metal Magnet - which smells like citric acid, not sure of the actual ingredients) or ascorbic acid. I prefer GLB Metal Magnet as it doesn't seem to have the high chlorine demand that ascorbic acid seems to have. This season, it's almost like my metal sequestrant is not working at all. I'm using Jack's Purple stuff. I have gone thru 4 bottles in the past month and the stains just keep coming back.

Here is a video I shot this weekend showing how effective GLB Metal Magnet is at removing the pool staining. I sent this video to the chemist that just did my water testing. They sent me an email asking to call but I missed them before they left for the day so I'll be calling them tomorrow.

Citric acid effect on pool stain - YouTube

A couple seasons, ago, I tried Jack's Stain ID kit and it indicated my stains are iron. I've basically run out of things to check. Nothing in my pool is corroding. I've checked the skimmer screws, the pool light, I even replaced my pool ladder with a polymer ladder to rule out corrosion from the ladder or hardware. I also re-hired my pool contractor to re-plump by pool equipment with additional Jandy never-lube valves that allow me to completely bypass my swimming pool heater to rule out any corrosion from the heater copper exchanger.

I'm thinking about turning off the salt chlorinator and just manually dosing the pool with liquid chlorine to see if the staining is reduced. Do you guys have any other suggestions or ideas?
 
GLB Metal Magnet is not really the right approach. It is mostly sodium sulfite (and oxygen and chlorine scavenger) and sodium erythorbate which is structurally and chemically similar to Vitamin C (it's also used as a meat preservative mainly in packaged corned beef). The erythorbate is what captures the metal ions. However, erythorbate is NOT stable in a chlorine environment and will breakdown very easily. Once it breaks down, the metal is easily released. The other MAJOR problem with that mixture is it should not be used with SWG because it adds a large amount of sulfates and sulfites to your pool water. Sulfates and sulfites can easily damage the metal coating on the SWG plates as well lead to advanced forms of sulfate corrosion inside your water heater. That is the most likely mode of how copper got into your water - mild chemical corrosion of the inside of your heat exchanger. After the water passed from your heat exchanger into you SWG cell, the SWG then oxidized the metal which led to stains in and around the wall and floor jets.

If I were you, I would pull your salt water cell and inspect the plates for damage. I would also stop using the GLB product. You should use either an HEDP (phosphonate) based sequestrant OR a polyacrylic acid (PAA) based one. Jack's Magic makes a copper removal kit that uses a sulfamic acid based treatment process that removes the copper stain but you should, for complete removal, drain the pool (as far as your practically can). That's the only way to ensure copper levels are fully reduced.

After your pool is refilled, you should carefully monitor copper levels (you might consider buying a test kit, or at least some strips). You should keep your pool's pH above 7.6 and try to keep your CSI near 0 or very slightly negative. If your heater core was chemically etch, a new passivating oxide layer will form but you need to keep your water properly balanced so it does not get acidic.
 
JoyfulNoise, thank you for the detailed reply. I'd like to clarify a few things...

I have only been using GLB Stain Magnet since AFTER I added the additional valves to bypass the pool heater from water circulation. Before that, I was using ascorbic acid but it would always put a high chlorine demand on the pool and tended to make the water cloudy for a few days after treatment.

I already drained most of the pool at the beginning of this pool season. I almost drained too much water as my liner started to shrink in the shallow end. To my surprise, it didn't seem like draining water helped as much as I hoped.

For the metal sequestrant, I use Jack's Purple Stuff... I thought that is an HEDP sequestrant.

I have used two copper test kits (one was drop based), one was paper strips. Both show almost no copper in the water as do the local pool stores and most recently, the folks at Periodic Products (the makers of the CuLator).

About the salt cell. Mine is clear so I can see the plates easily and they look perfectly fine, they're not even showing signs of scaling as they do mid-way through the season.
 
Thanks for clarifying the order.

I would still suggest you stop using the GLB product as sulfates/sulfites are not good for an SWG.

HEDP is not going to remove any current stains. For that, you need a stain removal system like the one Jacks has (sulfamic acid based).

I'm not at all surprised that the test kits are not measuring copper. If you have any sequestrants in the water sample, they will interfere with the test. There are only very few test kits that can detect metals with a sequestrant present as it usually requires an oxidizing acid digestion process (nitric acid) to first destroy the sequestrant and the release the metal. If you are seeing stains, your water has metals in it; measuring and detecting those metals can be tricky.


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Hi Carlos. I will have to look up everything from last year when I have more time, but can you tell us what happens if for, say 5 days straight you hold ph to 7.2. Give that a whirl and report fluctuations and stain appearance each day.

It would also be a good refresher to post a full set of your test results.


Ps..re old thread....send that pic of your rust stains in swg to the mfg and ask them what they think is going on...I'm not familiar with that cell, but the stains would have me wondering. Grasping at straws, but do you also have a check valve between te heater and chlorinator? Have you ever had someone test the bonding around the pool?
 
We developed a metal staining problem a few years ago that was covering our liner. I'm pretty sure our issue came from using an algaecide that had copper in it. We were new pool owners and in a cycle of non-stop algae and trying whatever the pool store recommended. We don't have an SWG, so I'm not sure if this will help you or not, but this is what has worked for us.

1. We did a couple of large water replacements in the pool trying to eliminate as many metals as possible. (It looks like you've already done this.)

2. I started maintaining the Ph between 7.2-7.4. The higher the Ph the easier it is for the metals to precipitate.

3. To remove the stains I did an ascorbic acid treatment. Before putting the ascorbic acid in the water, I used a Polyquat algaecide to try and prevent an algae bloom, then I let my FC drop to almost zero. Once the FC was low I put my filter on recirculate and added the ascorbic acid and let it run until the stains were lifted. After the treatment I slowly began raising my FC again. If you raise it too fast the stains may reappear.

4. For my setup I started using Jack's Magic The Pink Stuff. The first year I didn't invest in one of their sequestering kits, but the next year I did and it's been much easier. I'm able to monitor exactly how much sequestering agent is in the water and am no longer guessing at if there is enough and pouring in bottles at a time $$$. When I see stains start to reappear I add enough Pink Stuff to bring it up to 20ppm. The Pink Stuff will also lift light staining, so there is no need to do an AA treatment. Then I monitor it and don't let it drift below 12 ppm. Keeping it in this range keeps the metals at bay in our pool.

5. I also started using Jack's Magic The Filter Fiber Stuff. The thinking behind using it is that when you add the sequestering agent and the metals bond to it, it becomes a larger particle. Then when you add the Fiber Stuff (through your skimmer) it increases your filter rate to help trap those larger particles and backwash them out, helping to remove them from your pool. When the stains start recurring, I dose the pool with The Pink Stuff up to 20ppm and add the appropriate amount of Fiber Stuff, then backwash 24 hours later. After a few seasons of fighting metal stains, I think that is when I really noticed that our metals weren't coming back as fast, once I started using the Fiber Stuff. Not sure if that's the reason or not, but I have continued using it.

At this point the metals still show up occasionally with mild staining on my skimmer box, returns, and a little on the liner, but it's manageable. I would also recommend calling Jack's Magic if you haven't already. That's what I finally did and they were very helpful. They laid out exactly what to do from the ascorbic acid treatment, to the sequestering agent and filter aid.
 
Swampwoman said:
Hi Carlos. I will have to look up everything from last year when I have more time, but can you tell us what happens if for, say 5 days straight you hold ph to 7.2. Give that a whirl and report fluctuations and stain appearance each day.

It would also be a good refresher to post a full set of your test results.


Ps..re old thread....send that pic of your rust stains in swg to the mfg and ask them what they think is going on...I'm not familiar with that cell, but the stains would have me wondering. Grasping at straws, but do you also have a check valve between te heater and chlorinator? Have you ever had someone test the bonding around the pool?
Click to expand...

I keep my ph between 7.2 and 7.3. If I let it creep up around 7.5, the stains get much worse.

There is plumbing in place that completely bypasses my pool heater until I'm actually heating the pool. I have not had the bonding professionally checked by I did add a sacrificial anode to the bonding (buried in soil near equipment).

Here's my latest testing:

FC 4.5
CC 0
pH 7.2
TA 90
CH 250
Cya 70
Salt 3300
 

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Those sure look like precipitated iron to me. Easy to remove and keep away unless your fill water is constantly replenishiong with iron laden water. Do you know at what level the iron is in your fill water (not your pool).
 
duraleigh said:
Those sure look like precipitated iron to me. Easy to remove and keep away unless your fill water is constantly replenishiong with iron laden water. Do you know at what level the iron is in your fill water (not your pool).
Click to expand...

I just had the water tested by the chemist at Periodic Products (the makers of CuLator). They tell me that their test WILL detect any metals (even if sequestered). They tested both my pool water as well as my fill water (city water, not a water well).

They said they found no iron and only .01 ppm copper in the source water.

The pool water showed no iron or copper but I have been using one of their CuLator Ultra (4ppm metal removal) bags.
 
amccleskey said:
4. For my setup I started using Jack's Magic The Pink Stuff. The first year I didn't invest in one of their sequestering kits, but the next year I did and it's been much easier. I'm able to monitor exactly how much sequestering agent is in the water and am no longer guessing at if there is enough and pouring in bottles at a time $$$. When I see stains start to reappear I add enough Pink Stuff to bring it up to 20ppm. The Pink Stuff will also lift light staining, so there is no need to do an AA treatment. Then I monitor it and don't let it drift below 12 ppm. Keeping it in this range keeps the metals at bay in our pool.

5. I also started using Jack's Magic The Filter Fiber Stuff. The thinking behind using it is that when you add the sequestering agent and the metals bond to it, it becomes a larger particle. Then when you add the Fiber Stuff (through your skimmer) it increases your filter rate to help trap those larger particles and backwash them out, helping to remove them from your pool. When the stains start recurring, I dose the pool with The Pink Stuff up to 20ppm and add the appropriate amount of Fiber Stuff, then backwash 24 hours later. After a few seasons of fighting metal stains, I think that is when I really noticed that our metals weren't coming back as fast, once I started using the Fiber Stuff. Not sure if that's the reason or not, but I have continued using it.
Click to expand...

I also use Jacks Purple Stuff, the Filter Fiber Stuff as well as their sequestrant test kit. When I last tested the sequestrant this past weekend, it was at 15ppm. However, I have added another bottle of Jacks Purple Stuff since that last test.
 
Hey Carlos, why not repost the pic of what the guts of your SWG looked like when you cleaned it last year. Someone might have ideas and see this new thread!

In terms of the swg cell stain, if that's not a rust stain, I'm a monkey's uncle ;) For the liner, my guess is the same. I can't quite believe there's no iron in your water. I'd want to know more about their testing.

Regarding my comment about a check valve (as opposed to bypass)....conventional wisdom has been that there is no need for a check valve between heater and swg. But during a long convo with a commercial ENG at Raypak on another unrelated matter, he'd commented that he thinks that approach is wrong because of incremental and ad hoc back pressure, eg when you backwash even with chlorinator and heater off, that makes a difference. But you're cartridge filter, so as I said, grasping at straws.

What does your cartridge filter look like when staining is active? Is it discolored like the liner?
 
Swampwoman said:
Hey Carlos, why not repost the pic of what the guts of your SWG looked like when you cleaned it last year. Someone might have ideas and see this new thread!

In terms of the swg cell stain, if that's not a rust stain, I'm a monkey's uncle ;) For the liner, my guess is the same. I can't quite believe there's no iron in your water. I'd want to know more about their testing.

Regarding my comment about a check valve (as opposed to bypass)....conventional wisdom has been that there is no need for a check valve between heater and swg. But during a long convo with a commercial ENG at Raypak on another unrelated matter, he'd commented that he thinks that approach is wrong because of incremental and ad hoc back pressure, eg when you backwash even with chlorinator and heater off, that makes a difference. But you're cartridge filter, so as I said, grasping at straws.

What does your cartridge filter look like when staining is active? Is it discolored like the liner?
Click to expand...

Here is the photo showing the base of the SWG cell and a photo of my in-floor cleaner distribution valve which is about 5-6 feet downstream from the SWG.

The inside of the filter and pump don't show staining.


FB6F96B6-C24D-4B17-9B53-04474F5635C7.jpg

FullSizeRender.jpg
 
Last edited:
They said they found no iron and only .01 ppm copper in the source water.
Click to expand...
Very strange. How did the iron then get into your pool and precipitate onto the surface? It came from somewhere and I can't think of any other source.
I can't quite believe there's no iron in your water. I'd want to know more about their testing.
Click to expand...
+1 on the statement above
 
Okay, Carlos, you've been in this quandary a while or I wouldn't be trotting out more complex and expensive suggestions.

But here goes - this Hanna Instruments iron checker is a middle of the road unit - not pro, but unlike the guess strips, not dependent on your ability to read minute color changes. Its range is 0-5 ppm. For the $50 it might help you get the straight of what's in your fill water and what's in your pool. You are in GA, known for red soil ;)

I have a similar meter to high phosphate due to sequestrant etc. and it is very reliable with reproducible results. It reads the color for you.

If you want one, here's where you can get it. And since I don't own one but like their meters, if it doesn't help you -- eg if it reads zero and we deduct youre dealing with copper -- I will buy it off you after you've tried it. i wouldnt mind having one anyway, but have gotten used to reading the strips...but I'm very calibrated to hints of color change as I work in design ;)

Hanna Instruments Checker Iron Colorimeter - Marine Depot

Once we figure out the metal, then the source, maybe you can get in front of this.

Can you take a pic of the inside of your skimmer?
Also, how old is your liner (looks young to me) and are your walls steel or polymer?
 

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