iron staining on vinyl liner how to prevent long term?

[Nathanoneill]

Ive been a pool owner for 5 years now, and feel like I've got a good handle on things, but I've reading a lot of posts here talking about iron staining on vinyl liners, from iron.



Each time I have had my water tested at the local pool store, the iron levels have shown zero.

My Pool ; 36,000 gallons, with a SWG.


My situation is that I have been able to easily and fairly quickly remove the stains, following instructions to use

-Ascorbic acid 4 lbs ( lowering chlorine prior to adding - or not... it was already @ 1.9 fcl ) , stains were gone within 4-6 hours...
-24 hrs later , add metal sequestrant 40 floz ,
- added 1 Culator pouch to each skimmer
-then maintain a 7.2pH , + low chlorine ( less than2ppm ) for about 10-14 days ,
-after 14 days then rebalance water to normal pH and TA / fCl.

My issue is that , having done all this, its now 14 days post AA treatment and I see that yellow stain starting to deposit on my steps and liner in some places ( its still kinda faint, but coming).
Current levels;

FC 6.1
pH 7.4
TA 76
CH 165
CYA 77
SALT 3600
TEMP 79deg

side note - of course 5oz of Polyquat every week

So Added another 32oz of Poolmate MetalOut this morning in the hope that it will prevent it from getting worse....again.

Stains are worse in the shallow end, which gets a good deal of sun, and the staining on the floor also seems to initially follow the path of the jets pushing water back in from the filter.

I had planned on adding 18oz of metal out Avery 14 days as a preventative, but is this too little to keep the iron in suspension?

Any help or guidance here is appreciated.

 

[PoolStored]

The best thing you can do is remove the water with metals and replace it with water without metals. Make sure the metals are sequestered when you remove the water...

 

[duraleigh]

Pooltored's advice is the best.

Short of that, perhaps you can keep the iron in suspension by carefully lowering your pH down to 7.0 and see what happens. If it stays in supension, simply keep the pH at 7.0 permanently......test pH daily to keep it at 7.0

 

[YippeeSkippy]

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

If you’ve got iron in your fill water, use Polyfill to remove it

EDIT: Found out this method only works if your iron is oxidized already, meaning it’s got a dull or bright green tint to the water, or a nasty brown tint. If you know you have iron in your fill water, but it isn’t oxidized yet, bring your pool to shock level and it’ll turn the telltale green...

www.troublefreepool.com

 

[Mdragger88]

Where is the iron coming from?
Have you gotten your fill water tested?
Are you on a well?
Anything rusting in your pool? (Light niche, ladder rung etc)
The best option is to identify & remove the source & replace the water with fresh if possible.
Has your culator pack changed color?
What type of filter do you have?

The instructions on that sequestrant product say 1qt/10k gal initially so you should have added like 2.5 qts for your 36k gal pool. Then almost 2qts/month thereafter

 

[Nathanoneill]

Where is the iron coming from? - UNKNOWN?
Have you gotten your fill water tested? Yes... local pool store shops zero iron/ copper etc.
Are you on a well? NO , not on well. City water.
Anything rusting in your pool? (Light niche, ladder rung etc), some small rust parts on ladder at water line.
The best option is to identify & remove the source & replace the water with fresh if possible.
Has your culator pack changed color? , hard to tell.... looks slightly blue.... but that would indicate copper and the stains look like iron
What type of filter do you have? Pentair Sand Filter

The instructions on that sequestrant product say 1qt/10k gal initially so you should have added like 2.5 qts for your 36k gal pool. Then almost 2qts/month thereafter
View attachment 526338

Thanks , I will keep adding more sequestrant... Ive answered your questions above.

 

[JoyfulNoise]

You live east of the Mississippi River, all water in your parts of the world will have iron in it. Municipal suppliers do not treat to remove iron. Their processing will remove some iron from the water just as a matter chemistry, but there will always be some left over. Pool stores are the least accurate test and so it’s not surprising that they say your water has no metals. If you want a real water test, you have to pay for it by sending samples to an independent water testing lab. Typical charges are around $100 plus shipping for standard water tests.

Your water has iron in it and iron gets added by fill water. If it rains and that rain water contacts to ground and gets into your pool, that too will add iron. There are probably no sources of iron free water where you live. You could install an iron and mineral filtration system on your main water feed to eliminate any future iron exposure but not many people want the expense of that. Rain water is really your only other option but it has to be added to the pool by lowering the water level first and then allowing the rain to refill the pool.

Sequestrants are not one time additions. There’s always a start up dose and then a regular maintenance dose. You have to maintain the sequestrant because it is broken down by chlorine oxidation.

 

[Mdragger88]

Thanks , I will keep adding more sequestrant... Ive answered your questions above.

You should definitely remove & repair/replace the rusty ladder parts asap to eliminate that as a cause.
Even a little rust can cause stains all over - they are unpredictable.
Certain sequestrants (jacks & metal magic) claim that they “crystallize/clump metals together” & in conjunction with adding cellulose fiber/de to your filter it is supposedly able to be caught by the filter & removed with each backwash. This works better for some than others. The de/cellulose fiber must be replenished after each backwash.
There’s not one single magic bullet here if fill water is to blame except get water trucked in.
If your fill water has trace iron in it you may need to do a combination of all the things listed in this article including periodic AA treatments & regularly using sequestrant.

Iron Fill Water Filter - Further Reading

www.google.com

You can attempt to determine if your fill water has iron by doing this experiment
Post in thread 'Metals in pool'
Metals in pool

Keep in mind that it is possible that you have both copper & iron stains.
Especially if you have ever used any copper containing products like tabs/chlorine with “blue “ in the name or copper containing algaecides. Or you could be like me & have it in your municipal water.
Our water report lists copper but they don’t have to include iron since it’s not considered a contaminant.
Your last water report should be publicly available.

 

[JoyfulNoise]

I’d say don’t even bother with “trucked in water”. Unless the water delivery you are purchasing comes with a guarantee of some type regarding the chemistry of the water, the most likely scenario is that they drive the empty water truck up to the nearest fire hydrant to your home. Then they fill with hydrant water and deliver that the last half-mile to your house. Truck water is only worth considering if you are on a private well and your well water is really bad or your well pump simply couldn’t handle filling a pool. Most well pumps are not designed for continuous use and you can easily burn one up trying to pump 20,000+ gallons of water.

The advice so far is solid - consider the source and how you can mitigate water use and focus on sequestrant maintenance.