Iron stains - an $850+ adventure (so far...) - Need help

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BlueWater6334

Bronze Supporter
May 31, 2023
18
Southeast Louisiana
Hello,

I started trying to rectify a swamp of a pool with heavy iron staining at the beginning of May. I'm at my wits end and thinking about getting quotes to fill in the pool with dirt and never have to deal with it again lol...

Long story as short as I can get it:

- Pool had very deep and dark iron stains for 7+ years
- Pool had old deteriorating heater attached. Removed the pool heater from plumbing, thinking it could be the source of metals.
- Pool was neglected and was a green swamp at the beginning of May
- Shocked and SLAM pool for ~2 weeks, water now crystal clear, but pool surface looks terrible with the stains.
- Attempted ascorbic acid treatment to remove iron stains (reacted to vitamin C tablets so I knew it was iron).
- Ended up using about 6.5 lbs ascorbic acid in addition to a bottle of polyquat 60
- Put a CuLator Ultra 4.0 in the pump basket to try to capture the iron
- Pool looks a lot better, best the pool has ever looked since buying the house (faint staining still visible, but light enough I can live with it, plus I already spent a ton of money).
- Added Jack's Purple Stuff sequesterant (32 oz.) and more polyquat 60 around May 18 or 19.
- Pool became very cloudy, ran pump/filter 24 hours a day until water cleared up (have been running the pump 24/7 since starting initial SLAM at beginning of May really). Took about 5-7 days for the water to clear up after adding Jack's Purple Stuff.
- Now that water is clear, see that algae growing in the pool. Black or very dark green spots appear all over the pool. Slightly lightens when brushed with stainless steel bristle brush.
- Need to get rid of algae, but also not supposed to shock/SLAM because of iron in the water with come out of solution?
- Shocked/SLAMed anyway because I needed to get rid of algae...
- SLAMing pool was very difficult because of the amount of ascorbic acid in the pool
- Ended up using many gallons of chlorine for the FC level to start holding. I'm talking like 25+ gallons of 10% liquid chlorine.
- FC eventually holds, but still have algae problem. So I need to SLAM, right?
- Water now has a slight tint to it after adding chlroine to shock level last night, I suspect from the iron being oxidized and staining is going to start happening again.
- Still have algae all over, I don't know if I should continue with SLAM or what.
- I'm already at nearly $1,000 spent and I'd hate to have to buy even more liquid chlorine.

Other details:
- Pool heater removed from plumbing completely.
- Water source is municipal/city, not a well or anything.
- Not entirely sure if iron or copper stains, I suspect iron because it reacted to the ascorbic acid, but maybe it's copper from the pool heater? Do pool heaters even use iron pipes?
- Running the pump nearly 24/7 for a month takes a toll on your electricity bill, who knew?

What should my next steps be? Thanks for any help!

Attached some pictures showing the difference in the pool.

May 16 picture is from before the AA treatment showing the iron stains.
Jun 1 picture shows how much nicer the color was a couple days ago.
Jun 3 (today) pictures show the color of the water returning to a nasty tinted color and some of the algae spots that exist. Color change likely from shocking the pool last night.
 

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You’re too late in the season for stain control. I suggest you get the pool SLAM’d and clear of algae and then forget about trying to lift the stains. When the pool season is over, we can help walk you through options for stain removal. It may be necessary to simply lift the stains and then dump the pool water to get rid of all the metals. Then refill and try to rig up a system where you fill with as much rain precipitation as possible. Rain water comes free of all impurities.

You’re driving yourself nuts and hating the pool because you’re trying to fight a losing battle. Just get it swimmable and enjoy it. If anyone complains about the stains you can tell them they’re welcome to go to another pool …

Heaters have copper coils in them, not iron.
 
Thanks for the reply.

> You’re too late in the season for stain control. I suggest you get the pool SLAM’d and clear of algae and then forget about trying to lift the stains.
Click to expand...

I suppose you're suggesting this because during the winter the water is cool enough to prohibit algae growth so I can do an ascorbic acid treatment without worry about algae (and subsequently needing to shock after)?

And by "winter", I mean Louisiana winter where we're talking 50-60 F on average.
 
BlueWater6334 said:
Thanks for the reply.



I suppose you're suggesting this because during the winter the water is cool enough to prohibit algae growth so I can do an ascorbic acid treatment without worry about algae (and subsequently needing to shock after)?
Click to expand...

Correct.

When the summer heat kicks in, which is probably early February for Louisiana (I was once in NOLA in late January and it was amazingly beautiful … the locals told me it wouldn’t last long …), you have little control over algae growth and algaecides can’t keep up with an algae bloom. So trying to do any kind of stain treatment that requires zero FC is a losing proposition. Considering the pool was left neglected and then you had a swamp to deal with, the water probably developed a healthy dose of iron simply from all the organic matter that accumulated in it. That’s why I suggested the likelihood of just lifting stains and then dumping the water - it’s too contaminated to rehabilitate.

Start working on a plan to capture as much rain water as you can. Even now, if you can lower the pool water level before an expected storm, you can use that free rain water to help get rid of contaminants. It’ll mean more work keeping the CYA levels up, but that can be easily solved using tablets in a floater or adding granular CYA as-needed.
 
Some have cast iron headers.

full
 
Well, thank you guys for your insights. I'm disappointed to have spent so much money on a losing battle, but at least I learned something.

Will try again at the end of the year I suppose.

This was the guide I was following, I don't know who has access to it, but might be useful to add a paragraph there about doing it outside of pool season or when the water is a certain temperature: Ascorbic Acid Treatment - Further Reading
 
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I’m going to say that the heater was probably not the culprit.

You live the south eastern US … all of your water sources are going to naturally have high iron levels as your soils are acidic in nature and there is a ton of organic matter that water will filter through before reaching the normal aquifer for your area. Municipal water suppliers do not typically treat raw water for iron because it is not considered a pollutant. So whatever iron remains in the water after processing it through their filtration and disinfection systems will be delivered to the end user. Municipal suppliers can easily have several ppm of iron in their water systems.

Your pool was also a swamp and neglected as you described in your original post. Organic matter and decaying matter will release lots of minerals into a water body. If there were any dead animals in the pool, then they will release contaminants as well. So the water was not free of any iron to begin with.

Your pool also as red brick coping … guess what makes bricks red? Iron. Rain water is incredibly soft and you get lots of it. That means those bricks themselves can leach iron into any rain water that contacts them. If that contact water then gets into your pool …. iron will too.

I’ll see about updating the Wiki page. Normally people ask a lot of questions about AA treatments and stain removal and that’s a good point to discuss timing. But I can see you point in making it more obvious.
 

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JoyfulNoise's explanations sound reasonable, but I'm no expert lol

Here's the heater with that panel removed. And a magnet sticks to everything in there.
 

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Most of the iron in the stains from the returns came from the heater.

The heater is not 100% the only source, but it is probably the source for more than 50% of the iron.

may_16_prior_to_aa_treatment-jpg.499799
 
Last edited:
BlueWater6334 said:
Hello,

I started trying to rectify a swamp of a pool with heavy iron staining at the beginning of May. I'm at my wits end and thinking about getting quotes to fill in the pool with dirt and never have to deal with it again lol...

Long story as short as I can get it:

- Pool had very deep and dark iron stains for 7+ years
- Pool had old deteriorating heater attached. Removed the pool heater from plumbing, thinking it could be the source of metals.
- Pool was neglected and was a green swamp at the beginning of May
- Shocked and SLAM pool for ~2 weeks, water now crystal clear, but pool surface looks terrible with the stains.
- Attempted ascorbic acid treatment to remove iron stains (reacted to vitamin C tablets so I knew it was iron).
- Ended up using about 6.5 lbs ascorbic acid in addition to a bottle of polyquat 60
- Put a CuLator Ultra 4.0 in the pump basket to try to capture the iron
- Pool looks a lot better, best the pool has ever looked since buying the house (faint staining still visible, but light enough I can live with it, plus I already spent a ton of money).
- Added Jack's Purple Stuff sequesterant (32 oz.) and more polyquat 60 around May 18 or 19.
- Pool became very cloudy, ran pump/filter 24 hours a day until water cleared up (have been running the pump 24/7 since starting initial SLAM at beginning of May really). Took about 5-7 days for the water to clear up after adding Jack's Purple Stuff.
- Now that water is clear, see that algae growing in the pool. Black or very dark green spots appear all over the pool. Slightly lightens when brushed with stainless steel bristle brush.
- Need to get rid of algae, but also not supposed to shock/SLAM because of iron in the water with come out of solution?
- Shocked/SLAMed anyway because I needed to get rid of algae...
- SLAMing pool was very difficult because of the amount of ascorbic acid in the pool
- Ended up using many gallons of chlorine for the FC level to start holding. I'm talking like 25+ gallons of 10% liquid chlorine.
- FC eventually holds, but still have algae problem. So I need to SLAM, right?
- Water now has a slight tint to it after adding chlroine to shock level last night, I suspect from the iron being oxidized and staining is going to start happening again.
- Still have algae all over, I don't know if I should continue with SLAM or what.
- I'm already at nearly $1,000 spent and I'd hate to have to buy even more liquid chlorine.

Other details:
- Pool heater removed from plumbing completely.
- Water source is municipal/city, not a well or anything.
- Not entirely sure if iron or copper stains, I suspect iron because it reacted to the ascorbic acid, but maybe it's copper from the pool heater? Do pool heaters even use iron pipes?
- Running the pump nearly 24/7 for a month takes a toll on your electricity bill, who knew?

What should my next steps be? Thanks for any help!

Attached some pictures showing the difference in the pool.

May 16 picture is from before the AA treatment showing the iron stains.
Jun 1 picture shows how much nicer the color was a couple days ago.
Jun 3 (today) pictures show the color of the water returning to a nasty tinted color and some of the algae spots that exist. Color change likely from shocking the pool last night.
Click to expand...
Wow...you just decribed what I am going through (have vinyl liner though), including the amount of liquid chlorine I have added (stay away from Walmart 10% jugs though - my local pool store has a 12%+ 5 gallon jugs which is waaaay better). I also posted separately about removing the flow to / from the heater as well but when I called the company (Rome Industries / AquaComfort), they claim that the heater core / evaporator coil is copper / nickel hence not contributing to the rusty water. In addition, I repaired the rust inside the liner last season by scraping / cleaning the rust and covering with POR15. No significant rusting around the skimmers / light housing.

Having said that do you know whether Copper will cause rusty stain / water? Just like you the stain disappears completely within seconds with ascorbic acid but can't continue to dump ascorbic acid 2-3 days. My current plan (just like you) is to get rid of the heater completely but wanted to confirm with folks here. Yes, this is stressing me out as this season, by far, has been really difficult. Let's get through this!
 
stay away from Walmart 10% jugs though - my local pool store has a 12%+ 5 gallon jugs which is waaaay better
Click to expand...

You're saying this because there's something wrong with the Walmart 10% jugs (this is what I've always used) or because you're getting chlorine cheaper at your pool store?

Having said that do you know whether Copper will cause rusty stain / water?
Click to expand...

I believe copper can cause staining, but I don't think it would be removed by ascorbic acid. I think ascorbic acid only reacts to iron, so if it goes away with ascorbic acid, then it must be iron. You can get this pack from Jack's Magic called a "Stain ID Kit" that includes 3 pouches of different stuff to try on a stain to identify what you're doing with.

My current plan (just like you) is to get rid of the heater completely but wanted to confirm with folks here.
Click to expand...

I took the water heater out of circulation and I don't notice my pool becoming any worse than it was. Before, I felt like the stains just kept getting worse and worse as time went by. The original ascorbic acid treatment I did helped a lot, but I still need to do another this winter.
 
As for the 10% walmart - this may be coincidence but the walmart Chlorine was not as effective (e.g., not clearing the water as quick or at all) and yes, cost-effective using 12.5% unless 10% is on same (I bought them on sale in the past but ended up spending more to get the 12.5% instead :) ). For example, 1 or 2 gallons of 12.5% worked beautifully but when I poured in 10% (a bit more obviously and based on pool math app), nothing happened. And some of the dates of the walmart (at least around here in NJ) chlorine seemed "old" whereas the pool store gets basically weekly (at least) delivery. Again, my "bad experience" may have been just coincidental (e.g., other chemicals not balancing). I am willing to try again.

As for the ascrobic acid, my pool improved a bit with more doses of sequestrant (used GLB this time but i typically use Jack's Purple) - mine is definitely iron. I thought I learned a lot over the years here but I didn't realize / recognize that ascorbic acid DOES NOT eliminate iron / rust stain at all and will eventually come back (hence using sequestrants to "bind" iron.
 

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