Iron Staining from outside sources (UPDATED)

[jamestalmage]

EDIT: Read to the bottom, my initial assumptions were wrong. I've got metal staining, probably from an outside source.

Purchased and remodeled home with a pool that hasn't been opened in 5 years. Total swamp. Hundreds of toads and frogs in residence.

After a partial drain and refill, SLAM went great. Water is crystal clear and OCLT passes.

There are, however, significant brown stains on the wall.

Keeping it at SLAM levels and scrubbing for a couple days hasn't had an easily noticeable impact (might be lightening, I can't tell).

Kids are anxious to jump in to the clear water, but I want to get rid of the staining (and my wife insists I do). I understand exceeding SLAM FC levels is not necessary for sterilizing the water, but would it speed up the process of lightening the walls?

I know chlorine can be hard on equipment. It's a fiberglass pool and titanium heat exchanger, so should be pretty resilient.

If exceeding SLAM FC would speed things up, what's a safe limit?

 

[ajw22]

The brown stains could be iron stains. Put a paste of vitamin C in a sock and rub it on the stain. If the stain lifts it is iron.

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The stains are not unsanitary. Let the kids swim in the stained pool.

 

[jamestalmage]

The brown stains could be iron stains. Put a paste of vitamin C in a sock and rub it on the stain. If the stain lifts it is iron.

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

The stains are not unsanitary. Let the kids swim in the stained pool.

They're definitely organic stains, and I'm aware they're sanitary... But the directions for removing organic stains say to keep it at SLAM levels. That's going to be uncomfortable swimming I think.

 

[PoolStored]

That's going to be uncomfortable swimming I think.

You won't notice a thing. FC up to SLAM level is safe to swim...

 

[jamestalmage]

Well,
Turns out it is iron staining. I was sure it wasn't. Municipal water, and no sign of iron deposits anywhere during the remodel: No staining of sidewalk or siding from sprinklers, no staining in sinks/tubs/showers, etc... My parents have lived on the same street for years and no iron issues.

I'm wondering if it is all from a gym weight that fell in and spent a year at the bottom. Or some rocks/sand that were blown in? Maybe a nail or two fell in during construction (didn't find any, but there was so much organic muck).

 

[ajw22]

Iron is in fertilizer. Lots of muck in the pool could have carried iron from the ground into it over 5 years.

I hope you are letting the kids swim.

 

[jamestalmage]

We've got really bad metal staining on the walls of our fiberglass pool. It was not a problem for the first 10 years of use for the previous owner, but when we shut down for a few years to remodel the house, and let it go into a swamp, the stains just showed up.

A couple possibilities:

1) Iron in my municipal water, but pool Ph was never so out of whack that stains appeared. I doubt this. The owner let it go swampy before he sold, but when he opened it to sell, the iron deposits weren't there. There's no sign of iron in my household plumbing. My parents have lived on the same street for 8 years and don't have iron issues.

2) The iron isn't from my municipal water supply, but an outside source. I suspect this. A couple of gym weights holding on the cover fell in and spent a year at the bottom of the pool. They look like they're plastic over concrete. There's no obvious mark where they were lying on the bottom (actually pretty white there). The entire surrounding patio was replaced, lots of sand and gravel made it's way into the pool. (But again, no dark stains where the pile of sand/gravel was, but it may have shifted around). I'm sure a few nails made it in (There ARE obvious see one or two of them were).

I'd like help determining if my reasoning above is sound, and if so, what my sequestrant strategy should be during my ascorbic acid treatment, and for ongoing maintenance.

My thinking is: Sequestrant as instructed during ascorbic acid treatment, and maintenance doses for the rest of the season. Followed by a generous drain during pool closing, and then stop worrying about it unless the stains return.

 

[jamestalmage]

They've been told they're allowed, but we just got hit with a cold snap in Michigan. High of 64, lows in the 40s tonight. So it became a lot less urgent for them.

 

[jamestalmage]

Also, I should mention:

Pool was closed for 4 1/2 years. So lots of time for outside iron to get in and build up.

As part of the swamp cleanup we did a near complete drain. Not recommended, I know, but I have some pretty intimate knowledge of the water table here, and I know it's at least 10 feet lower than the bottom of my pool (we dug a deep basement, and there's zero hydrostatic pressure all the way down... I could get away without a sump pump, except the city requires it).

Thinking this might be relevant since I think the iron is outside sources. I've probably already removed it.

Do I even need sequestrant at this point? Is the iron in the stains sufficient to saturate fresh municipal water?

 

[JoyfulNoise]

Typically you don't want to do any SLAM'ing of the pool after a stain removal process or else you risk the stains coming back. So you need to get the pool clean and clear as quickly as possible and then do a metal stain removal process .

Sequestrants are ABSOLUTELY REQUIRED.

Time and again this point gets missed. If you lift stains off of a surface where they get redissolved into the water and do not drain the pool of that water, then when you start to raise the chlorine, the stains will come right back. Sequestrants are needed to HOLD the metal ions in solution or else they will simply precipitate back out.

So, please follow the Ascorbic Acid stain removal process and use a good quality sequestering agent. You will need to use a full start-up dose of sequestrant when the time comes as well as have enough on hand to do maintenance dosing. If you can drain lots of water at the end of the season in anticipation of winter precipitation, then you can start up next season without sequestrant.

 

[jamestalmage]

I understand the broad strokes of how metal staining works, and why sequestrants are necessary.

My question was more around how much of the iron that was in the pool water was deposited as stain. If only a small percentage was deposited as stain, then I've already drained most of the iron away when I did a complete drain.

 

[mknauss]

Typically when the chemistry of the water gets at the point that staining occurs, the bulk of the metal in the dissolved state plates out as a stain. Once you reintroduce that metal to the water, you need to sequest it, or remove it.