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Thread: A question about metals and sequestrant

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    Join Date
    Oct 2009
    Location
    Apex, NC
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    Question A question about metals and sequestrant

    Split from Well Water Zea3

    This is what I learned from this post. Please let me know if this is wrong. Iron that is oxidized (from chlorine) will stain pool surfaces. Adding acids like ascorbic or citric acid will form a salt type molecule that lifts the iron from the pool surface. It is still in the water but as an invisible salt. Iron in this salt form will eventuly come out of solution and stain again when it is oxidized by the chlorine (breaks down the salt molecule). Putting in a sequestriant will bind the iron salt molecules with the sequestrient which will inhibit (temporarily) the iron oxidation from chorine. Since the chlorine is continually trying to oxidize (or breakdown) the iron salt sequestriant matter you need to keep replenishing the sequestriant which is expensive.
    Given that I have one questions:
    Is there a affordable and user friendly test for "bad" form of iron that can be monitored so we can only add sequesrient when needed. The so called maintenance dose is obviously designed to insure over-kill

    Sorry for the over -kill on my post but I need to wrap my brain around the science here. Any help is appreciated.
    I have been to the pool school and also rea/re-read the very extensive posts on staining.
    Call me Jerry
    In-ground Plaster/Marcite
    18,000 gallons
    Well water
    Salt sanitizer - Sand Filter

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    Join Date
    Sep 2013
    Location
    Connecticut
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    Re: Well Water

    The point I was trying to make, re filtering, was that it is worth trying to filter (and put up with the ugly water for a number of days), rather than hiding the problem right away with a sequestrant. In some cases you may be lucky enough to have your regular filter pull it out (as we do), so it's worth exploring. In other cases people have to resort to extra filtration. Finally, there are pools that require a continual dose of sequestrants.

    So, have you ever looked at your filter to see if it is catching any of the rusty material?

    Edited to add: Above was in response to the original poster's questions, not Jerry's questions about metal staining. I don't think the OP had an issue with stains on pool surfaces.
    18' x 48" ring top pool (Summer Escapes); 5500 gallons; set up June - October, stored during winter; Intex 2500 gph pump (B size cartridge filter) Hayward 21" sand filter + 1.5 hp single speed Powerflo Matrix pump (upgrade October 2016) *** K-2006 test kit, refills from tftestkits

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    Re: Well Water

    I'm ok with the filtering option. When they last measure iron at the pool supplier they got 0.1 (I assume ppm) That doesn't sound like a lot but it probably doesn't measure the total iron that could precipitate. Whether I use sequest or filter I was wondering if there is a practical way to measure what is necessary so I only filter or or add sequester when necessary. I don't want to wait for the stains to appear first and I can't afford the so-called maintenance doses.

    Another question: I have done the citric acid cleaning once. It cleaned the stains perfectly and also lowered the PH quite a bit - definitely acid level <7. I let it sit a day and then added PH increaser to get it above 7. I then went swiimming. A day later and ended up itching like crazy. It could have been chigger bites as I was mowing a field of high grass. (It is non-stop into the pool after mowing believe me) I use copious s insect repellent but in the back of my mind I'm thinking it is a reaction to the citric acid. ( I've checked previous threads oin itching and there is no shortage of itching theories. Bottom line I don't want to have to do the acid treatment repeatedly. I'm hoping I can manage the seques doses economically.

    Sorry if I plugged into the wrong OP question. I have been a regular reader but only the first time I've posted.
    Call me Jerry
    In-ground Plaster/Marcite
    18,000 gallons
    Well water
    Salt sanitizer - Sand Filter

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    Join Date
    Sep 2013
    Location
    Connecticut
    Posts
    728

    Re: Well Water

    Hi Jerry, and welcome to TFP!

    This site works better if you start a new thread with your specific questions - even if your concerns overlap with the OP's, they are not identical. You've already touched on several issues she didn't express concern about. Also, the two pools aren't the same - you have a plaster pool surface; she has vinyl; she has a seasonal pool; you don't... It gets confusing to mix two people's questions together, as you can imagine.
    18' x 48" ring top pool (Summer Escapes); 5500 gallons; set up June - October, stored during winter; Intex 2500 gph pump (B size cartridge filter) Hayward 21" sand filter + 1.5 hp single speed Powerflo Matrix pump (upgrade October 2016) *** K-2006 test kit, refills from tftestkits

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