Fiberglass pool Staining issues - AA treatment and metal remover

[JP Lemelin]

Hi! I'm new to TFP forums but it seems to had a lot of experienced people there concerning pool maintenance!

So I will try my shot if someone can help it will be much appreciated! By the way, I'm a french canadian from quebec and the english is not my primary language so excuse me for that in advance for my writing skills.

So let's begin, I have installed in my backyard a brand new fiberglass pool at the beginning of the summer and I didn't have any problems for the first 3 months. My water chemistry were good and everything was balance (I check the chemistry every week). I have a salt chlorinator and I maintain everything in the good parameter.

After 3 months, I realized that my pool walls and steps were yellowing a little bit. So I waited and the end of the summer (right now), to making a AA treatment for removing the stains (that's what my fiberglass company told me to do). I was pretty sure the stains come from my backyards construction (installing concrete paver around the pool etc...). By the way, I have a pool defender inline anode wiring to a pole in the ground so it helps to prevent positive ions in the pool.

Before I used the AA treatment (citric acid), I was making sure that my water chemistry was good for making the treatment and here's the parameter:

Alkalinity: 80 ppm
Hardness calcium: 200 ppm
pH: 7.2
Chlorine: 0 ppm
Phosphate: 0 ppm
Iron: 0.0 ppm
Cooper: 0.0 ppm

So, I start my AA treatment in the pool and I was making sure that my pump was still running 24/24 for this process. A day later, the stains disaspear and the pool was really clear so, after that I brush the walls and clean the pool. After that, I put a Metal control to the pool for making sure that my metallic particles will be in suspension and my sand filter will take the majority of the metal particles.

I waited 1 week before adding chlorine with my salt generator and the day after I did that, my pool turned yellow/green. And I didn't make any shock chlorine, I just started my salt generator at the minimum and my pH level were at 6.3.

After that, I saw that the stains have reappered at the same spot and were yellow. So I realized that I don't have removed entirely the metals in the pool and that reaction was probably cause by oxidation (if i'm not wrong because i'm not an expert).

So, i bring a sample to my pool store to check if I have metal particles in the pool and surprisingly, there's none and the agent of the pool store told me it's probably algea that have growth but i doubt it because i did this AA treatment at this time of the year because I'm from Canada, and right know the pool temperature is approximatively 62. And the pool turned yellow/green pretty clear right after I start my salt chlorinator and the day later I was at 0.7 ppm chlorine.

Now, I wanted to get rid of the yellow/green water from my pool (see photo from attach files) and i tried the cuLator metal eliminator in my pump strainer and I put polyfill fiber in my skimmer. And, the same day i gradually rebalanced my pH, alkanity and chlorine really slowly. The day after that, the pool was really better and my Culator pouch was brown color and my polyfill too so I presumed that I have iron right?

So I write this message, to have some help in the future of what I did wrong or what should I do to remove the stains if it's really iron. Because I supposed it's this, but I'm not an expert and by the way, I didn't fill the pool with a well, the water came from a municipality water.

Thank you in advance!

 

[Texas Splash]

Welcome to TFP! The color of the water, and fact tat your AA treatment seemed to work, would indicate you do have iron in the water. Pool store testing is often wrong in all areas. Another DIY test is to rub a Vitamin C tablet on the steps or area of the shell that is discolored. Vitamin C works very well against iron. With iron, you can try to filter some out with polyfill as long as it's not bound to a sequestrant, but your sand filter won't do much. You mentioned a pH of 6.3? Not sure how you got that number, but if it is below 7.0 I would not let it stay there. That's much too corrosive for the water and equipment.

Accurate water testing is exceptionally important for any pool, but especially one that may have metals. You need spot-on FC and pH tests for sure. In addition, you may need to conduct an Overnight Chlorine Loss Test to ensure you don't have algae. While your season is almost over, a proper test kit with results is very important. The test kit will still be good next season.

 

[Texas Splash]

Be sure to bookmark our Pool Care Basics, update your signature with all of your pool and equipment info, and see the links below for additional info. As for test kits, in Canada Taylor has control, so you'll want to look for the Taylor K-2006C test kit unless you have access to shipping in the states at which point a TF-Series test kit is ideal (see my signature for link).

Swimming Pool Test Kits Compared

What pool test kit should I buy? Why shouldn't I use test strips? Our recommended test kits will pay for themselves in no time!

www.troublefreepool.com

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

Create Your Signature - Further Reading

www.troublefreepool.com

 

[JP Lemelin]

Welcome to TFP! The color of the water, and fact tat your AA treatment seemed to work, would indicate you do have iron in the water. Pool store testing is often wrong in all areas. Another DIY test is to rub a Vitamin C tablet on the steps or area of the shell that is discolored. Vitamin C works very well against iron. With iron, you can try to filter some out with polyfill as long as it's not bound to a sequestrant, but your sand filter won't do much. You mentioned a pH of 6.3? Not sure how you got that number, but if it is below 7.0 I would not let it stay there. That's much too corrosive for the water and equipment.

Accurate water testing is exceptionally important for any pool, but especially one that may have metals. You need spot-on FC and pH tests for sure. In addition, you may need to conduct an Overnight Chlorine Loss Test to ensure you don't have algae. While your season is almost over, a proper test kit with results is very important. The test kit will still be good next season.

Hi thank you Texas splash for you're answer!

I just tried the vitamin C tablets and yes, i works but not totally, it's lighten the stains very much so i presume that it is in fact, iron.

When you say to try some polyfill as long as it's not bound to a sequestrant (by sequestrant you mean a metal remover?)

And yes i mentionned that I had a 6.3 ph before I turned my slat chlorinator because i let the AA treatment and metal remover for a week to making sure that it will remove a lot of stains. I think it does because before I backwashed my sandfilter, i was like 3 PSI more than usual. Next time, should I run the treatment for like 3 days? Of course when i did the AA treatment I know that will drop significantly my pH so I was already on bypass on my pool heater and my salt chlorinator was off.

When you mean a test kit, you are talking about the test kit chlorine and ph right? Because I already have a numeric ph tester that i calibrated every 3 weeks and a chlorine tester.

What can you suggest me to do the next open season to remove entirely the iron stains from my pool? Run another AA treatment and drain the pool in half with filtered water?

Thank you again!

 

[Texas Splash]

by sequestrant you mean a metal remover?

Correct. Many of those stain removal products simply try to lift a stain while keeping it in solution. If that's the case for you, any iron protected by the metal remover probably won't get filtered out until the remover product wears out.

Below is one example of a successful polyfill method.

From brown to 😍😍. Thank you polyfil!

We filled our pool from our well. We knew the risks and knew we would have a battle when the water was 12" deep as it looked green from the metals. Our fears were confirmed when we added chlorine and the water turned brown almost immediately. Enter 5 gallon polyfil filter. It worked...

www.troublefreepool.com

Here is a TFP article on AA. It's not a 3 day process. Relatively fast actually once you see the results.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

When you mean a test kit, you are talking about the test kit chlorine and ph right?

Not just FC and pH, but either a TF-series test kit or Taylor K-2006C. Any other pH meter you have is fine and will compliment a full test kit, but you'll eventually want to have one.

What can you suggest me to do the next open season to remove entirely the iron stains from my pool? Run another AA treatment and drain the pool in half with filtered water?

That depends on the source of your iron and cost of fill water. If you're on a well, that's where the iron is coming from. If not, perhaps old plumbing or simply city water with a high iron content. The AA link above is great and I would follow that. The trick is once the staining is lifted to exchange as much water with fresh (non-iron) water as possible, otherwise you're right back ion the same boat next season.

 

[JP Lemelin]

Correct. Many of those stain removal products simply try to lift a stain while keeping it in solution. If that's the case for you, any iron protected by the metal remover probably won't get filtered out until the remover product wears out.

Below is one example of a successful polyfill method.

From brown to 😍😍. Thank you polyfil!

We filled our pool from our well. We knew the risks and knew we would have a battle when the water was 12" deep as it looked green from the metals. Our fears were confirmed when we added chlorine and the water turned brown almost immediately. Enter 5 gallon polyfil filter. It worked...

www.troublefreepool.com

Here is a TFP article on AA. It's not a 3 day process. Relatively fast actually once you see the results.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

Not just FC and pH, but either a TF-series test kit or Taylor K-2006C. Any other pH meter you have is fine and will compliment a full test kit, but you'll eventually want to have one.


That depends on the source of your iron and cost of fill water. If you're on a well, that's where the iron is coming from. If not, perhaps old plumbing or simply city water with a high iron content. The AA link above is great and I would follow that. The trick is once the staining is lifted to exchange as much water with fresh (non-iron) water as possible, otherwise you're right back ion the same boat next season.

Thank you for you're help it's really appreciated!

But when i got to the pool store, they tell me to put shock chlorine on the pool that will help remove the yellow/green water color and I was really sceptic because I knew that it was iron and not algae. Anyways, I put like 75 grams of chlorine power (70% concentrate) to higher my chlorine and know it's at 3 ppm and I have 7.4 ph. Is it too much and did I make a bad decision?

Right know, how can I resolve my color water green/yellow? Let the Culator Eliminator do the job with a polyfill in the skimmer and eventually in weeks it would make the water clear? And balance the alkanility to 80 ppm, 7.2 ph and 1-2 ppm of chlorine?

Another thing, can we used a flocculant or clarifier to help remove iron from the pool easily? Because of what a read, the iron is still in the water even if we used a sequestrant?

So it will not be the best to make an AA treatment to remove iron stains and after that drain the pool in half with new water without iron? Because the primary reason that I got iron in the pool (I Think) it's because I did a lot of concrete paver cut with the saw and obviously, it makes a lot of particles in the air with iron minerals in it that goes to the pool.

Thank you again for your respond and taking the time to answer me!

 

[Texas Splash]

chlorine and know it's at 3 ppm and I have 7.4 ph. Is it too much and did I make a bad decision?

Probably not. Always go back to the FC/CYA Levels. That chart is key to know where your FC should be. The pool store won't tell you about this relationship.

Right know, how can I resolve my color water green/yellow? Let the Culator Eliminator do the job with a polyfill in the skimmer and eventually in weeks it would make the water clear? And balance the alkanility to 80 ppm, 7.2 ph and 1-2 ppm of chlorine?

Depending on the amount and consistency of the iron, some can get filtered, some not. Sometimes it's not right away. Much depends on the condition of the iron. But it can't hurt to use the polyfill. Balance the chemicals line normal per our Pool Care Basics articles.

can we used a flocculant or clarifier

I would not. Those products will only complicate matters.

So it will not be the best to make an AA treatment to remove iron stains and after that drain the pool in half with new water without iron?

Once you complete a successful AA treatment, the more water you can "safely" exchange, the better. Soon you'll close for the winter and you might be able to refill some of it from snow/rain.

Remember, above all else, accurate at-home water testing is key. Either by using a Taylor K_2006C or TF-Series test kit from the US, you need one of those. Unless you are buying a specialty item like a toy or chair, avoid the pool store testing and advice. It will only frustrate you.

 

[JP Lemelin]

Thank you a lot for you're answers! Last question, does citric acid or abscorbic acid damage the gelcoat from a fiberglass? (Of course with the right quantities for the pool)

And what works best for iron AA or CA?

Thank you

 

[Texas Splash]

Those products should be safe for your gelcoat, but I would stick to ascorbic for all the reasons listed in the AA article below. Hope that helps.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

 

[JP Lemelin]

Those products should be safe for your gelcoat, but I would stick to ascorbic for all the reasons listed in the AA article below. Hope that helps.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

Hi again Texas,

I was wondering if the calcium hardness is required in a modern fiberglass pool like mine? The reason is I have like 50 ppm of calcium hardness right now but I want to know if this parameter should be absolutely at 200 ppm? What can a low calcium can do to a fiberglass pool?

Thanks in advance!

 

[Texas Splash]

I was wondering if the calcium hardness is required in a modern fiberglass pool like mine? The reason is I have like 50 ppm of calcium hardness right now but I want to know if this parameter should be absolutely at 200 ppm? What can a low calcium can do to a fiberglass pool?

Today's FG shells are not fabricated with plaster products that we know of, therefore "technically" the gelcoat (just like vinyl) does not require calcium. The exceptions to that would be if you have a waterline tile or perhaps a heater that requires a minimum CH level. That, along with a certain degree of stain protection from some minerals (i.e. cobalt), is why TFP places a minimum CH of about 200 or so.

 

[JP Lemelin]

Today's FG shells are not fabricated with plaster products that we know of, therefore "technically" the gelcoat (just like vinyl) does not require calcium. The exceptions to that would be if you have a waterline tile or perhaps a heater that requires a minimum CH level. That, along with a certain degree of stain protection from some minerals (i.e. cobalt), is why TFP places a minimum CH of about 200 or so.

Hi Texas, I hope you're doing well! I need your advice again because I did my AA treatment at the beginning of the season and everything was fine until the end of the season and now I have staining issues again. But, my staining issues before was iron only and know even if I put AA on the stain it won't disappear (powder or tablets directly on the stain with pool water at 7.6 PH). I tried with dry acid to see if it's copper, nothing happen and i tried with a trichlor puck to see if it was organic (nothing either).

I'm pretty sure it's iron staining again but, this time it's seems pretty difficult to remove it (See pictures attached). Before doing a AA treatment again, can you suggest me something else to try? Like diluting some muriatic acid and spray the water line if it can be removed? Or you think maybe it's the natural discoloration of the fiberglass shell? I heard that MA is used to clean fiberglass pool shell when the staining is hard to remove.

For you're information, it's been my second season with this pool and the surface are still smooth when I touch it. And my water parameter for the overall season was:

Alkalinity: 80-120 ppm
Hardness calcium: 100-150 ppm
pH: 7.6-7.8
Chlorine: 2 ppm

Thank you in advance for you're help!

 

[Texas Splash]

If the stains don't react to Vitamin C, then it's fairly safe to rule out iron. That stuff along the waterline almost looks like a scum line of sorts. Have you tried a Magic Eraser? Your FC level is quite low for just about any CYA level. May not be directly related to the stains, but be sure to follow the FC/CYA Levels. I suspect you're closing soon with the water getting colder I imagine unless you are still using the heater?

 

[JP Lemelin]

If the stains don't react to Vitamin C, then it's fairly safe to rule out iron. That stuff along the waterline almost looks like a scum line of sorts. Have you tried a Magic Eraser? Your FC level is quite low for just about any CYA level. May not be directly related to the stains, but be sure to follow the FC/CYA Levels. I suspect you're closing soon with the water getting colder I imagine unless you are still using the heater?

I don't have used my heater for the summer, but i tried the vitamin c and hold it a little bit longer. It's seems to have lighten the stains but not completely, is it because my PH is to high to react completely to remove the stains?
Alright I will follow up for the FC/CYA level! And yes the water is colder but I don't close the pool soon, I like to close it later to keep the water clean.
I tried the magic eraser before and did nothing..
But for the muriatic, did you know if it can help to remove the stains better than AA if its diluted?
Thanks in advance.

 

[Texas Splash]

It's seems to have lighten the stains but not completely,

You may have something other than an iron issue. You may want to consider a Jacks ID Stain Kit.