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Thread: Partially Drain to Reduce Metal?

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    Partially Drain to Reduce Metal?

    I've got a fiberglass pool that's right on the edge of a marsh. They had a tuff time digging the whole because it kept filling w/ water.

    I've got recurring problems w/ iron staining on the fiberglass. I'm getting set to go w/ the Ascorbic acid treatment, but was wondering if I might get a head start by partially draining the pool to reduce the iron concentration in the water.

    Among other sources, I've used a long rusted snake to try and clear my skimmer line.

    1. Is this a good theory...to reduce the iron concentration. Will it make a big difference?

    2. How much can I drain the pool before it becomes hazardous to popping out of the ground?

    Andrew
    Pool: 10K Gallon Fiberglass w/ SWG and cart filter.

    Spa: 400G D1 w/ Ozone, Vision (Silver Ion).

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    Re: Partially Drain to Reduce Metal?

    I would like others to give their input here to be certain but I kind of doubt that the drain snake would add enough iron in the water to result in staining levels of iron being present in the water. Rather, I would look to the fill water to be a more likely source. Are you filling from a well? If so, and the well water is high in iron, you may continue to run into the same problems. A metal sequestrant might be the way to go in that case.

    Sounds like your proximity to the marsh would make draining your pool a touchy thing at best. I'll defer to the experts here for the best advice.

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    JasonLion's Avatar
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    Re: Partially Drain to Reduce Metal?

    I would get your fill water tested for iron before doing any water replacement. Fill water is by far the most likely source of iron in the pool.

    If your fill water doesn't have any iron, then water replacement is a good idea. If you do end up doing some water replacement, you will need to be careful not to let the water level get very far below where it is now.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Partially Drain to Reduce Metal?

    If you do decide to drain you want to do it AFTER the ascorbic acid and seqesterant. If you do it while the pool is stained then much of the iron is going to be in the form of stain on the pool and not in the water. If you are on the edge of a marsh I would consult your pool builder about what you need to do to drain. It might need special procedures and might not be worth the effort. You an do a series of dilutions by dropping your water level slightly below the skimmer (NO MORE than a foot and in your case possibly less!) and refilling (perhaps overfillling slightly) but this will be a slow procedure and will require a lot of these drain and refill cycles.

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    Re: Partially Drain to Reduce Metal?

    Thanks guys...

    No well water involved...straight city water.

    Just had a test for iron, and ur right. No detected levels, I guess its all in the fiberglass! So yes any drain/refill would be best done after the fiberglass is clean and iron is suspended in the water.

    The guy at the pool store didn't seem to think draining was a great idea so close to the water table. I'll just try to be more religious about keeping the sequestrant levels up w/ the monthly doses.
    Pool: 10K Gallon Fiberglass w/ SWG and cart filter.

    Spa: 400G D1 w/ Ozone, Vision (Silver Ion).

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    JasonLion's Avatar
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    Re: Partially Drain to Reduce Metal?

    Draining, in the sense of lowering the water level is not a good idea. But replacing water does not require lowering the water level. You could use continuous dilution, where water is added at one end of the pool at the same time that water is removed at the other end of the pool. You do need to keep an eye on things to make sure that the rates match up and the water level remains fairly stable, but other than that it works fairly well. Continuous dilution does use a little more water than drain and refill. For example a 50% replacement requires using 75% of the pool size of water.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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