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Thread: How much Chlorine do you use?

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    Richard320's Avatar
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    How much Chlorine do you use?

    I spent several hours tending the pool last Wednesday. I added 2 cups of 10% liquid Chlorine to get the level up from ~15 to 20. High CYA indicates target of 14-21. So then things were busy at work, not getting home until after dark. And Sunday was a full day with some other stuff. This morning, Monday, I checked pH and Cl. pH is dead on at 7.5, same as Wednesday. Chlorine dropped to 10-12. I have to dilute the sample. I took one reading at 1:4, another at 1:5. It indicates I need to add close to half a gallon of Chlorine. Is this extreme?

    It has been warm and sunny, 80F, and the pool is in sunlight pretty much all day long. Water temp is 58F.

    Is this a normal amount of Chlorine to add, based on your experience, or is something amiss?

    PS: Pool is 16000 gallons
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Mod Squad Bama Rambler's Avatar
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    Re: How much Chlorine do you use?

    It seems about right to me. During the summer with full sun I loose about 2ppm per day. From Wednesday to Monday that's at least 4 days, so at 2 ppm per day that's 8 ppm lost. That's right in line with what you lost. You could do an overnight chlorine drop test but I'm not sure the loss you're seeing calls for it.

    P.S. You really need to get a FAS-DPD kit so you don't have to dilute the sample.
    Dave J. TFP Moderator
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    JasonLion's Avatar
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    Re: How much Chlorine do you use?

    You need to keep in mind that test results using dilution can be wildly imprecise. All of the possible sources of error get multiplied by the dilution, which means that your test results are +-5 at the very best, and probably much worse than that. A difference of 10 between tests is within the testing error, and so might not mean anything. All of this would be much simpler to figure out if you got a FAS-DPD chlorine test, such as the one in the TF100 from TFTestKits.net. The FAS-DPD chlorine test is far more precise than any approach using dilution.

    You should also be working on getting the CYA level down (unless I have completely misunderstood). CYA levels over 80 can be extremely problematic. With CYA at 180, shock level is at least 38, which would be a huge amount of chlorine. There are also a number of other problems with high CYA level, for example it is impossible to determine CYA level over 100 with any precision, the required high FC levels can compromise the PH test, etc. By far the best thing is to bring the CYA level down to something more reasonable.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Richard320's Avatar
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    Re: How much Chlorine do you use?

    Quote Originally Posted by JasonLion
    You should also be working on getting the CYA level down (unless I have completely misunderstood). CYA levels over 80 can be extremely problematic. With CYA at 180, shock level is at least 38, which would be a huge amount of chlorine. There are also a number of other problems with high CYA level, for example it is impossible to determine CYA level over 100 with any precision, the required high FC levels can compromise the PH test, etc. By far the best thing is to bring the CYA level down to something more reasonable.
    I know. But I'm also stuck in a drought zone. Once the water restrictions are eased, I can drain and refill. But if I do so now, it will be wildly expensive (about $250to lose half the water), and probably also earn me a $100 restrictor installed on my water meter - installed at my expense!
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: How much Chlorine do you use?

    Is having water trucked in an option for you?
    45,180 gallon 26' x 53' IG Vinyl, irregular shape. Hayward sand filter / pump. Polaris AutoClear SWG, supplemented with a Hayward Automatic Chlorinator (In-Line). Hayward 400K BTU heater. Paramount "turnover" system. Polaris 480 PRO cleaner.

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