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Thread: Are these iron stains?

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    Question Are these iron stains?

    Hello everyone. I have an above ground oval pool with a vinyl liner with a DE filter. I switched to the TFP method about 3 years ago. Prior to the TFP method, I was constantly fighting algae and shocking the pool with bags of shock from the pool store at least every week. Now that I've taken control of the pool, it's been mostly Trouble Free™. My question is regarding stains observed on my wedding cake stairs and on the liner itself. I noticed them last year but cleaning the stairs removed the stains. But now I see them again and I decided to see what the stains are. I tried the crushed vitamin C tablet and sure enough it removed the stains from the stairs (see pictures).

    I also purchased the Taylor iron test kit and it showed 0 ppm in the pool water. I fill the pool water with municipal water which is sourced from surface water, so I wasn't expecting iron coming from that. I'm at a loss as to where I could get the iron stain, unless it's not really iron. The only odd thing I use that could be contributing are the drainage stones I put in the cylinder in the stair weight. I'm closing the pool on Saturday so I'll address the staining in the pool in the spring. I don't have a heater which could cause copper staining and I have borax in the water @ 50 ppm (if that's important).

    Does anyone have any clues as to what I'm dealing with?

    The stones look like this:
    3_4-drain-rock1.jpg

    Stairs after vitamin C tablet
    stairs1.jpgstairs2.jpg

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    pabeader's Avatar
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    Re: Are these iron stains?

    I have an oddball question. What color is the dirt around your house and pool?
    Bob - Palm Beach by San Juan Pools. approx 5000 gals Pentair 320 cartridge filter (all new guts installed by me) Goldline SWG Intermec 104 TImer Test kit: TF-100 w/Speed Stir

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    Mod Squad Texas Splash's Avatar
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    Re: Are these iron stains?

    I'm no expert on the stones or aggregate being used, but for the iron testing, you might consider testing the source water and not testing the water already in the pool (chlorinated). Once chlorine precipitates the iron in the water, the test may be faulty, so it's best to test the source before any chlorine hits it. That doesn't help with the stone issue, but should confirm the municipal water is iron-free. I suppose next year you could try a difference method of weighing-down the steps to see if there is any difference between the new method and the stones from before?
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Re: Are these iron stains?

    Thanks for the replies. There's no exposed dirt around the pool. Surrounding the pool is pea stone and beyond that for 2/3 of the pool is a patio and grass for the remaining 1/3. I'll test the water from the outdoor faucet I use to fill the pool after work today.

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    Mod Squad pooldv's Avatar
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    Re: Are these iron stains?

    It sure looks like iron staining and the Vit C test backs that up. It could be from a low level iron from rocks, we've seen that before. It could also be from a low level of iron in your fill water. Iron will build up over time. Consider capturing rain water or diverting gutters to the pool for a iron-free source of water to replace evaporation and splash out. More here, Pool School - Stains in Your Pool
    TFP Moderator
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: Are these iron stains?

    I tested my fill water and no iron registered on the test. So I'm leaning towards the rocks I have in the weight in the stairs. Next spring I plan on addressing the staining in the pool. Does this sound like a plan? Upon opening and adding enough fill water, I'll make sure the pH is ~7.2. Then start adding ascorbic acid 1/2 lb at a time until the stains disappear. At this point, would I need to use a sequestrant like Jack's Magic The Pink Stuff? Would using a product like CU Later help and would I need to use the pink stuff with it or not?

    Thanks for the help guys. This forum is great.

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    Mod Squad pooldv's Avatar
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    Re: Are these iron stains?

    If the source of the iron is the rocks then the best course of action would be to do the ascorbic acid treatment to life the stains and do a partial drain to remove the iron from the pool. Then you won't need to use a sequestrant or CUlator. With a vinyl liner pool be sure to leave a foot of water in the shallow end when draining to prevent liner shrinking and shifting.

    You can add your pool info to your signature so that we can better help you. More here, Pool School - Read This BEFORE You Post
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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