Iron Stains driving me crazy!

[doug9105]

I need help! I've had my pool for about 7 years, and until about 2 years ago it was a dream. I'm not dumb (well, at least I can read pretty good, lol) I'm an attorney who actually took basic chemistry and organic chemistry classes in college, but these iron stains are kicking my tail, and taking all the fun out of owning this pool, and I need advice.

First off, there isn't any iron in my fill water; believe me, I've had it tested several times, by 3 separate pool supply stores in my area. I'm on city water and top off the pool about once a week with a garden hose. My pool is surrounded by a 3 foot strip of concrete on all sides, and a 3 foot flower bed outside that. I don't see any way that iron could be getting in from an external source.

I believe the iron got into my pool 3 seasons ago when, in a moment of stupidity, I replaced a small plastic hose clamp on my Polaris 280 sweeper with a "stainless steel" one from my workshop, fully intending to swap it for a plastic one in a day or 2. I completely forgot about it, and when I was putting the sweeper in storage for the winter 3-4 months later, I noticed that the bolt on the clamp was badly rusted. So this rusty thing had been swimming around in my pool all summer. I had noticed a little "tea-colored" staining that had appeared on the white pool steps just before I closed the pool, but thought maybe it was just from some cheap 3" chlorine tabs I had purchased at Wal-Mart, and didn't think much about it. Sure enough, when I opened the pool the following spring, as soon as I shocked the pool, I had dark orange-yellow iron stains all over the place. This had never happened before.

I did my research and have been fighting a 2 year battle with these iron stains. In the process, I have learned a lot about pool care, and to be fair, the iron stains never get as bad as they did that first time, but it is rare that I can go over 2-3 weeks without them trying to come back.

Here's my usual monthly attack on the stains: when I start seeing the white steps turn yellow or "tea colored" I turn off the auto-chlorinator and let the chlorine levels drop off to about 1ppm. this usually takes several days, and by this time the steps and other white work in the pool is really yellow. Then I backwash the filter, put the pump on re-circulate, and add 1 pound of ascorbic acid. After a couple of hours, most of the stains are completely gone, and I add a bottle of Jack's Magic Pink Stuff, and set the pump to filter. I also turn the auto-chlorinator back on. After that, I add the recommended maintenance dosage of Jack's every week, hoping to keep the iron sequestered. I test my water frequently, and keep my PH between 7.2-7.6, and my FC levels around 2-3 ppm. I also keep the other levels, like alkalinity, etc. within the recommended ranges.

If I'm lucky, I have a stain free pool for 2-3 weeks, but then, without fail, the yellow stains on the steps start coming back. I've tried everything I can think of; extra Jack's (it just made the water cloudy) running my chlorine levels lower at 1-2 ppm (the pool turned green) and even those Ferrous-Tabs that are supposed to remove the iron from the water (no difference at all).

I've removed basically all phosphates from my pool with a regular regime of DE added to my sand filter, and my pool never turns green any more, but having to use ascorbic acid so often leaves my FC levels chronically low, and so I'm constantly fighting cloudy water. About the time that my FC levels get to the point where the water clears up, you guessed it, the stains start coming back. Trying to add liquid chlorine a little at a time does keep the water clear, but the stains just come back faster.

I was to the point of just draining my pool and re-filling, but have been told that would be a disaster. I've even considered switching over to a salt-water generator for sanitation, but to be honest, I don't really see how that would help, since even though it might make it easier to keep my FC levels balanced (all my friends have switched over to salt and love it) I don't think that would help with the recurring stains. I never dreamed that this would turn into so much trouble. None of my pool-owning friends have this problem, and the local pool-supply stores have no advice other than telling me to use ascorbic acid on the stains (which I already know) and trying to sell me bottles of some new "metal-magnet" product guaranteed to remove the iron from my water once and for all (it doesn't).

Could someone please help? I don't know if I'm even on the right track. Is there any other possible reason for these stains? Or is there any way to get off the AA/Jack's Magic merry-go-round? I truly appreciate any advice you can give me.

doug9105 - 18x36 18,500 gallon in-ground pool, vinyl liner, Hayward pump and sand filter, Polaris 280 sweeper running off Hayward auxiliary pump, using auto-chlorinator with 3" Pool-Life Tabs for sanitation.

 

[JohnT]

Welcome to TFP!

Sounds like you are doing what needs to be done, but I suspect you haven't identified the source of your iron.

I don't really think the rust from a single hose clamp is the source of the iron in the water.

It may be that the iron content of your fill water is variable. Sudden, large water usage or flushing of the lines can disturb sediment and raise the metal content of the water.

 

[max2k]

... Here's my usual monthly attack on the stains: when I start seeing the white steps turn yellow or "tea colored" I turn off the auto-chlorinator and let the chlorine levels drop off to about 1ppm. this usually takes several days, and by this time the steps and other white work in the pool is really yellow.

are you sure it's not biological? I'm just surprised chlorine concentration has such effect on it. How do you test your water? Pool stores are well known for inaccurate results. If it was me I'd stop adding anything to the water except liquid bleach, ordered one of recommended test kits and run my own tests to see what's up. This forum advocates for very simple approach to pool care but it's up to you to decide what you'd like to follow.

I was to the point of just draining my pool and re-filling, but have been told that would be a disaster.

Why? High water table? Do you drain/refill over winter?

 

[duraleigh]

The iron rust from a hose clamp did not cause your iron issues.

If you are dead certain the issue is iron (and I think it is), then you have to find the source. Once you do that, it will be a solvable problem

 

[robertmee]

Also, you mention switching over to a SWG...That will likely make no difference. A salt water pool is still chlorine. Since you're a chemistry geek, you'll understand that the SWG through electrolysis is simply liberating the CL from NaCL. The Water and NaCL becomes Hydrogen gas and Hypochlorous acid. The gas escapes as bubbles, and the Hypochlorous acid (chlorine) bonds to organic matter and combines back to form salt again. Rinse and repeat. So, you'll still have staining issues with a SWG, because your staining is a result of Chlorine attaching to the ferrite.

And per Mr. Dave, the rusty clamp is not your source. We had to replace our liner this year due to a bad install last year, and the water truck filled up with municipal water. It was heavy with iron, and upon filling our pool it was a lovely shade of green. Not knowing any better, I assumed algae and proceeded to SLAM the pool (Shock) with high FC. Immediately, I had a lot of iron precipitate out of the pool to where I almost had a full layer of rust on the pool floor. I kept the FC high, sucked up as much to waste with a vacuum as I could, let our pool robot get the rest, and after about a week's time with NO sequestrate, the pool was crystal clear....as the Sand Filter with some DE did the rest. Point is, unless you have a constant source of iron, it's not going to cause this problem over 2 years from a rusty clamp.

Based on my experience, I would raise my FC to SLAM levels....That's based on your CYA which you haven't reported. Let all the iron precipitate out, and filter/vacuum it out. If it returns, then you've got an ongoing source of iron.

Here's a link to my IRON thread including pictures of what I was removing from the water:

New Water that's green??

 

[doug9105]

First, I want to thank everyone for the quick responses to my post. Next, since the consensus seems to be that I've got iron coming from somewhere, let's assume for a minute that it's coming from my source water (i.e. the garden hose I use to top off my pool with city water). I think my first step will be to eliminate this as the potential problem. Yesterday I bought a filter that screws onto the end of my garden hose. The local pool store told me it would filter out iron and other trace metals, and that I should start topping off the pool by sticking the hose (with this filter attached) into my skimmer basket instead of adding water directly into the pool. That way, the source water will have to pass through both the new hose filter and also the sand filter with added DE before it makes it into my pool. If my goal is to keep from adding more metal to the pool every time I top it off, is this a step in the right direction? Or is it even possible to filter out iron while it's still sequestered in the source water? And if so, are any of these hose filters any better than the rest? Again, thanks to everyone for any and all help!

 

[JohnT]

Filtering out metals seems to be almost magical. Sometimes for some people some filters work. The more you can get out, the better. There is also the Cu-later absorbent product for the skimmer to consider.

 

[robertmee]

Per my post above I was successful in filtering it out with a combination of vacuuming as much to waste as I could after raising the FC to high levels to make as much iron precipitate that was going to. And then running my pool robot and sand filter with some DE 24/7. The water cleared in about 6 days doing this (only vacuuming the first 2 days), and it probably took 2 weeks until the deep end no longer had a greenish tint.

 

[26venus]

One thing you mentioned in your first post was that you had the iron content tested by three different "pool stores". Were the readings consistent? Most folks that contribute to this forum have little to no trust in pool store testing. I would suggest that since you are filling your pool from a municipal source you contact them for a chemistry report. It should be available to the public upon request. Or maybe a simple call to the water service authority and someone there could give you the exact amount of iron in the water.

 

[robertmee]

One thing you mentioned in your first post was that you had the iron content tested by three different "pool stores". Were the readings consistent? Most folks that contribute to this forum have little to no trust in pool store testing. I would suggest that since you are filling your pool from a municipal source you contact them for a chemistry report. It should be available to the public upon request. Or maybe a simple call to the water service authority and someone there could give you the exact amount of iron in the water.

In general that's true, but for the most part, the pool stores get metal content and salt content pretty good, so if three stores were consistent, I'd go with it.

 

[smforte]

Hi Doug....hopefully Swampwoman will be along to help you. She's the metals guru around here...but I so feel your pain. I have the exact same problem and have been on the AA and sequestrant merry go round for over two years. It got so expensive I finally gave up. I bought a foreclosure so no idea what was done or used previously. The liner was a beautiful blue though and no iron stains that I could see. The only thing I contribute the stains to was a stainless ladder that seemed to have some corrosion around the water line. I removed it last year. Ive tired everything, have never used an Algecide etc. I keep my ph on the low side and only use bleach or liquid chlorine. What I find strange is when I dropped a vitamin c pill on the liner several months ago that small spot looks beautiful and the stain never returned there. After 3 AA treatments and sequestrants I'm at a loss. My stains never precipitatie out to the point I can just vacuum them out. They just stain the whole liner and steps a light yellow. I may try a Metal Magic treat next. GOOD LUCK!

 

[AnAltruist]

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