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.