Iron Stains never ending battle, Jacks Purple no help? Partial help? EDITED WITH RESULTS, POST #1

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diy_darryl

Well-known member
Jul 20, 2014
52
St. Louis, Missouri
Hello, we have fought iron staining in our fiberglass pool for years. Have done the Ascorbic Acid treatment many times, poured in way more Jacks Purple than called for and they just keep coming back.
We keep an eye on FC levels after treatment and it still returns even with all parameters close to optimum.
Tired of spending so much $$$ on sequestrant and poured the last remaining bottle in this Spring. We are having the iron start precipitating back into the surface worse than ever and even before our FC has stabilized really (after AA treatment). I am guessing that Jacks had been helping somewhat but this is a never ending battle.
Over the winter we finally put in a water softener with 3 stage whole house filtration but it’s as bad as ever or worse.

Is there any solution to filter the fill water enough to get the iron out? County Water from Wells.

EDIT: Not sure if the whole house filtration helped or the fact that we finally followed the procedure EXACTLY, bought a sequestrant test kit and adding a maintenance dose of Jacks Purple weekly. The iron stains have NOT returned in the slightest (but neither has the chlorine production in the SWG). We have an IC20 SWG and only a 7-8000 gallon pool and have cranked it up to 70% (usually much less is sufficient) and still adding bleach. We had to dump 4 lbs of Citric Acid in to get rid of the stains (way more than normal) but that should have been ate up long ago. SWG was replaced NEW last year and was working before the AA treatment. CYA is 70 and salt is 3650.
 
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diy_darryl said:
Is there any solution to filter the fill water enough to get the iron out? County Water from Wells.
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Each iron scenario is different. It sounds as though the iron content has gotten so high it's very difficult to manage in chlorinated water. We understand that even if you could get non-iron water delivered by truck, you don't have the option of emptying your FG pool, only a portion of it. That might help, but it's no guarantee. I suspect with your new water softener, you may have to do several water exchanges over time to lower the iron content.

Have you had any luck with polyfill?
 
diy_darryl said:
We have tried polyfill in the skimmer with no discernible difference.
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That's unfortunate. In your situation the metal goes straight to the pool's surface without the ability to mechanically filter. Besides controlling the FC as you noted above, have you been able to keep the pH under control?
 
Some tips about iron, hopefully some are helpful to you.
  • CuLators 1.0's and 4.0's can help (but only if the metals are sequestered) to remove the metals, but they probably won't get everything before staining happens and it takes -weeks- for them to work (so not an immediate or short-term fix).
  • If you don't have a DE filter, adding DE to your sand/cartridge filters, or adding Jack's Filter Fiber should allow you to catch more of the metals due to them catching lower micron junk than a standard sand or cartridge filter can't do by itself.
  • If iron/metals are coming from your auto-fill or fill water, taking steps with pre-filtering before it gets into your pool can reduce metals in your pool (installing a softener -should- actually prevent iron from getting into your pool water).
  • Running polyfill in your filters helps remove some iron/metals but ONLY if its been oxidized and falls from solution to suspension (coloring your water green) but again, by that time, chances are the staining will occur before you remove ALL of it. Polyfill works for most people, but not for everyone (maybe it's because some have too low a pH to catch iron in the polyfill? or because their iron ppm is too small? Not sure...)
  • A lower pH (7.0-7.4 consistently) can help will preventing staining, but if your CH is also really high, it might not help as much as you might hope because the water can only absorb so many minerals until they fall out. If you're NOT a plaster pool (and are fiberglass or vinyl), than this is much easier as you can keep your CH lower, as you don't care about CSI like us plaster pool people do.
  • Keeping FC on the lower end (still within your FC/CYA standards) WILL help because it allows the metals to stay in solution. When your FC goes up too high, the metals go from solution into suspension and turn your water color and likely will start to stain IF you don't back them back into solution quick enough or filter them out (through your filter or polyfill) quick enough too.
  • Draining water may help, but it's not a solution (more of a band aid) if the metals are still getting into your pool through other means (and there's more means than JUST by auto-fills), despite what people often lead you to believe.
  • Some pools (depending on design, covers, etc.) have a LOT more evaporation (or leaks even) than others, which means, more auto-filling, which again will be problematic if there's iron in your auto-fills (which you shouldn't have with your softener) because you'll just keep re-adding more metal into the pool.
  • On large SWG pools, salt could add some metals into the pool. Even if your salt is 99% pure, when you're adding 720+ pounds of salt into a large pool, even 99% purity means a lot of other crud (and metals) may still be getting into your pool! (this is often overlooked I think)
  • AA treatments are neat, but they suck having to do mid-summer because of the havoc on the AA cancelling out your chlorine and vice versa, and for 2-4 days you might be battling getting your chlorine up, with regular FC dosing, but you CANNOT overshoot, or you'll just take all the metal and put it back into suspension. And certain sequestrants you might use (and you really do need to use them when doing an AA treatment!!), like Jack's Magenta (which is stronger than their Purple stuff) will react to Polyquat-60 (if you use that) and cause a ton of cloudiness in your pool quickly too, which can take a week or more to get out, so that's another headache.
  • Jack's Purple Stuff should be helping to keep your iron sequestered, but no sequestrant is perfect (especially if your FC is on the higher side of your FC/CYA ratio target).
  • It can help to use Jack's "Sequest test kit" to validate your sequestrant PPM values to make sure you HIT the right dosing for every week's maintenance dosing (which you need to do as sequestrants will break down and when it does, expect iron staining problems, as I'm sure you're well aware...
  • For AA treatments, you can buy 5 pounds bags of Vitamin-C for as CHEAP as $27.37 at DudeDiesel (way cheaper than pool store "treatments"). so that as least LOWERS your cost when you need to do AA treatments.
  • Finding the SOURCE of your iron is important. Is it getting in from the fill water or auto-fill water? Coming from other possible areas like coping/pavers/rocks/boulders/wind, etc.? I strongly encourage you to verify if your fill or auto-fill contains iron or not.
HTH.

EDIT: you can still get iron in your pool eve with a softener, -IF- you don't have a dual-tank softener, where one tank is still softnening while the other is regenerating. If you have a single tank, its possible you are auto-filling during a regeneration, which means, you would be adding potential iron (and calcium hardness) into your pool during those regenerations.
 
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I would say yes, but others may think otherwise. DE filters seem to trap smaller micro stuff than cartridge or sand. Though you can add DE to a cartridge or sand filter, if necessary. I had a DE filter previously, but switched to cartridge for ease of use/cleaning/assembly. I always had too much trouble with those darn grid things for putting it back together.
 
I have an in ground white fiberglass pool 23,000 gallon 16'X36' depth 3'-8' since 97 when we bought house. Pool was put in 80-81 believe it was called an Ester Williams. Had it re-gel coat 2015, lasted till 2022. Last year had Ecofinish put on looked great, had some areas that company will take care of (off season). This year noticed dark brown blotches mainly on vertical part of stairs but small ones else wheres. Checked it out and used vitamin C did the trick. Got some ascorbic acid at pool store. Added it to pool as instructed used Mikes Magic blue after acid, and pool fluff filter. After a day or two running pump, back washed pool looked great spots gone. After 4-5 days noticed a brownish ring around pool. Checked an area with ascorbic acid and presto ring disappears. I am on well water so not a great mystery where coming from but never had this bad an issue. How do you keep all metal out of pool once stains removed?
Thanks for any thoughts on the matter.
 
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