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Thread: Best way to reduce chlorine level

  1. #1
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    Best way to reduce chlorine level

    A week ago, I shocked my pool after having a pool party for my son.

    For the last week it has only rained and very little with very little sunshine. I've kept my pool covered and ran the pump and SWG for 10 hours a day.

    Today, I tested my water and my TC is well in excess of 10. When I added the yellow OTO drops, the water turned red!!!

    What is the best way to reduce the chlorine level? I think I will simply leave the cover off, turn the SWG off and let the sun do its magic until the levels reduce.

    Can anyone suggest any other tips?

    Thanks.

  2. #2
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    Re: Best way to reduce chlorine level

    Sounds like a plan.

    Have you read Pool School?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
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  3. #3
    Junior Member pool_hokie's Avatar
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    Re: Best way to reduce chlorine level

    How can you reduce chlorine without sun? I need to get the level down in my hot tub, there's no sun here in winter, and I can't leave the cover off.

    I want to say you can use ammonia, but I don't know for sure, or what amount.

    Any ideas?

  4. #4
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    Re: Best way to reduce chlorine level

    pool_hokie,

    Elevated chlorine is not necessarily bad. VERY HIGH chlorine can be an issue. How high is it?
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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  5. #5
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    Re: Best way to reduce chlorine level

    And OTO only test total chlorine which is how much is combined and free together. If the Free is only 5 and total is 10, you need to bring up the free to 50 or use MPS to get rid of the combined. If it happens again the next day with little or no usage,, something is going on like phosphates and a water change is in your future.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  6. #6
    Junior Member pool_hokie's Avatar
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    Re: Best way to reduce chlorine level

    It's way high - turns dark yellowish orange on one drop on an OTO test and is well over 10 ppm on a DPD (didn't want to use up all my drops to figure it out exactly). CYA is also near zero. This is a covered hot tub.

    Nothing strange going on - neighbor put an extra cup and a half of bleach in the hot tub while we were away.

    Jack's Magic makes a chlorine neutralizer - there's some non-pool product you can use as well, just wondering if anyone knows what it is.

  7. #7
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    Re: Best way to reduce chlorine level

    Sodium thiosulfate lowers chlorine levels. Leslies sells it for $11.00 for 3 pounds.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

  8. #8
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    Re: Best way to reduce chlorine level

    I don't think there is much Combined Chlorine (CC) in this situation. It's the Free Chlorine (FC) that is excessively high due to running the SWG when there wasn't much sun and the water was cool so chlorine usage was very low.

    I would suggest first turning off the SWG if you have not already done so. As for lowering the chlorine level in a hurry, either in a pool or in a spa, one can use a chlorine neutralizer (sodium thiosulfate). Alternatively, you can use hydrogen peroxide (especially for the spa since the quantities are far lower) where a 3% hydrogen peroxide solution neutralizes approximately the same volume of 6% bleach. So to neutralize 10 ppm FC in 10,000 gallons, it would take around 26 cups (1.6 gallons) of 3% hydrogen peroxide in 10,000 gallons or about 1 cup in 350 gallons. You can get stronger hydrogen peroxide for the pool, though usually one just uses sodium thiosulfate instead at a rough rate of 2.6 ounces weight of sodium thiosulfate to lower 1 ppm FC in 10,000 gallons.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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  9. #9
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    Re: Best way to reduce chlorine level

    Thiosulfate wipes out chlorine too. I use it just before dumping a pool for service. Keeps the EPA and NJDEP off my back. They don't like it when 20K+ gallons of chlorinated water gets dumped in the sewer. Something about causing fish kills makes the environmentalists get upset. I wonder why?

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  10. #10
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    Re: Best way to reduce chlorine level

    Sodium Metabisulfite does the same and is considered food grade. You can buy a 50# bag at www.galladechem.com for about $35.00.

    Happy New Year!

  11. #11
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    Re: Best way to reduce chlorine level

    The dosage for sodium metabisulfite is around 1.5 ounces (weight) per 10,000 gallons for a 1 ppm FC reduction. For sodium sulfite (another alternative) it's 2.4 ounces and as I mentioned above, for sodium thiosulfate it's 2.6 ounces. You should add about half the required amount and then retest after an hour of circulation. These amounts are approximate since multiple chemical reactions can occur depending on the pH and mixing conditions.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  12. #12
    Junior Member pool_hokie's Avatar
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    Re: Best way to reduce chlorine level

    Thanks for the info!

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