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Thread: Best Time Of Day To Add Bleach? And Why Is It The Best Time?

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    Best Time Of Day To Add Bleach? And Why Is It The Best Time?

    I see many here seem to add bleach in the evening or at night.

    Just wondering what your thoughts are on the best time is to add bleach. I forget sometimes at night, and then add in the morning. (the bleach adding in the morning certainly has less time to lose concentration in the pool before the harsh sun, than that added at night 12 hours before)

    And why is the time you add bleach the best time?

    Thanks for your thoughts,

    Jeff
    40 x 16 (28k gallon) plaster pool, Intelliflo VF pump, Hayward 48 sq. ft. DE filter, using Purifiber, using BBB, TF-100 test kit

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    Barbara C's Avatar
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    Re: When Is The Best Time Of Day To Add Bleach?

    I add in the evening to get my Cl level back up for the night and ready for the next day. Unless you have organics in the pool, you aren't going to lose much chlorine overnight. If you wait until morning, then there is the potential to give algae a chance to get started because of low levels.
    24' AG Vinyl
    13,500 gallons
    1hp Hayward pump
    Sand filter
    Jug dumper apprentice

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    Re: When Is The Best Time Of Day To Add Bleach?

    Best time is either after sunset, or when you need it.

    I'll explain....

    Bleach doesn't lose concentration overnight unless it has something to work on. In fact, a good way to tell if your pool is in good shape is to do an overnight chlorine test. Ideally, the FC at night should be the same as the FC level the next morning. If not, it indicates some organics in the water that need killin'. Adding chlorine at night means that the chlorine you add will be useful for attacking the organics and won't be broken down by sunlight.

    That said... if you measure a low FC level in the morning, you shouldn't wait until evening to add the bleach -- you want to keep the chlorine level up during the day. Algae loves to grow in warm, sunny water, and without chlorine to keep it in check, things can get out of hand fairly quickly.

    15x33x54 Oval AG
    15000USG
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    Re: When Is The Best Time Of Day To Add Bleach?

    Quote Originally Posted by Barbara C
    I add in the evening to get my Cl level back up for the night and ready for the next day. Unless you have organics in the pool, you aren't going to lose much chlorine overnight. If you wait until morning, then there is the potential to give algae a chance to get started because of low levels.
    Ahh..... you beat me to it by 4 minutes

    15x33x54 Oval AG
    15000USG
    Hayward 3/4hp pump
    Hayward 22" sand filter
    BBB

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    Floater's Avatar
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    Re: When Is The Best Time Of Day To Add Bleach?

    I like to bleach as soon as the pool doesn't receive anymore sunlight, so obviously that means early evening for me. It is also when I have my pump run the most up to about 11:00pm. I think having the max quota of bleach in the pool overnight to kill anything that intruded in during the day gives it a good balance.

    I also add it then because we use it during the day and again, this lets it circulate in the evening once everyone is out. If we have a late evening, I just add and leave the pool running until the next morning. I have not been able to add sometimes in the evening and do so in the morning and I don't think it hurts it at all . I just know to run the pump after I do.

    It is probably really preference and what works best for the individual. I don't like changing my clothes twice before going to work if I accidently spill some bleach on me as well!
    ~_~ Sherry ~_~
    24' Round AGP, 13,500gal, 1.5hp Hayward
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    Re: When Is The Best Time Of Day To Add Bleach?

    I guess I'm not quite as structured as most of you! I see the logic in adding it in the evening, but I add it whenever I get to it. Sometimes in the evening, sometimes in the morning, sometimes in the afternoon...I've never noticed a difference.
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    Re: When Is The Best Time Of Day To Add Bleach?

    Usually in the evening when the sun is off the water.

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    JasonLion's Avatar
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    Re: Best Time Of Day To Add Bleach? And Why Is It The Best Time?

    The difference between adding in the morning and adding in the evening is real, but small. If morning is much better for you then by all means add in the morning. If you don't really care, then add in the evening.
    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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