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Thread: When and how often to add liquid chlorine?

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    When and how often to add liquid chlorine?

    I'm a fairly new pool owner. I've been using trichlor the last year but I adjust chlorine levels with liquid chlorine. Usually the 10% stuff.
    So I am going to stop using trichlor because it's raising my CYA. I have a sand filter so I do backwash often so over a little time, I should be able to lower the CYA from 65 to a more manageable 40 or so.
    Should I add liquid chlorine in the morning or the evening or both? Is there a better time do add chlorine??? How fast does it dissipate?

    Thanks
    Mesa Arizona. Old school 26,000 gallon in ground plaster pool with sand filter built in 1984.

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    Re: When and how often to add liquid chlorine?

    You really need a good test kit to know how much chlorine is needed to safely and effectively sanitize your pool. You can find a couple of recommendations in the pool school section of this site. That will easily tell you how much chlorine is being used up on a daily basis and w/that information and the pool calculator here as well, you will know exactly what you need to add.
    Indiana, ABG 24'x52" Galveston by Blue Cascade (Craigslist buy w/part of deck included), 13,500 gallons, Intex SWG, solar panels mix 2, TF-100 test kit.

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    Re: When and how often to add liquid chlorine?

    Thanks for the quick reply.
    I do have a test kit and I test first thing in the mornings and many times in the early evenings.
    I know how to test but I was just wondering when and how often to put bleach in. Once every day? Split between morning and the evening? Do I just test several times a day and add as needed?
    Mesa Arizona. Old school 26,000 gallon in ground plaster pool with sand filter built in 1984.

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    linen's Avatar
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    Re: When and how often to add liquid chlorine?

    Quote Originally Posted by Mesamav
    Should I add liquid chlorine in the morning or the evening or both? Is there a better time do add chlorine??? How fast does it dissipate?
    Evening is best, as long as you add enough extra so you are still at your recommended FC level (for you cya level) the next night.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Richard320's Avatar
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    Re: When and how often to add liquid chlorine?

    It's all trial-and-error. Let's say you start at 5, add enough to get you to 7, and 24 hours later you're at 4. You didn't add enough; with CYA at 65, minimum FC is 5. You dipped below that. It will only take you a week or two to know your usual consumption. By the way, 65 CYA is not too high if it's real hot and sunny. Knowing your typical consumption, you can get lazy - we all do, eventually. You'll be able to skip testing once in a while and just dump in the usual amount. And you'll also be alerted if consumption suddenly goes up without a good reason, like a pool party with 8 6 year old boys or something.

    They key is to add enough to keep the FC above the minimum for your CYA level until you can add more. Pool Calculator is your friend, bookmark it. Big party? Load up 2 or 3 ppm beforehand.
    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: When and how often to add liquid chlorine?

    While I'm on the subject,
    I have a sand filter, I live in the Phoenix area so it gets sizzling during the summer, my pool is in direct sunlight virtually from sun-up to sundown so chlorine consumption probably will be a little high compared to others.
    I know you guys frown on using trichlor and I understand the reasons why. It adds CYA. Other than adding the CYA, is there any other reason it isn't good for the water???? I gotta admit, it is terribly easy to use but if it creates other problems as well, I'd like to know because with all the dust around here, I'm constantly backwashing my sand filter. I typically backwash more than I should because the water around here has so much calcium. My calcium level in the pool is in the high 400's and my tap water is 200 so calcium builds up pretty quickly. I lose 1/2 inch of water daily during the summer because the humidity is 15% or less. Our humidity a few days ago was 4%. It doesn't get much drier than that. Add in our typical heat and a little wind here and there and your water goes down pretty quickly.
    So there's the story.
    With that said, if the CYA stays stable because of how much I backwash, is there other reasons not to use trichlor?

    Just curious.
    Mesa Arizona. Old school 26,000 gallon in ground plaster pool with sand filter built in 1984.

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    Richard320's Avatar
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    Re: When and how often to add liquid chlorine?

    Quote Originally Posted by Mesamav
    With that said, if the CYA stays stable because of how much I backwash, is there other reasons not to use trichlor?

    Just curious.
    Nope. I change out a lot of water for CH also, and I'll use pucks to bring the CYA back up. As long as you monitor things, it's okay.
    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: When and how often to add liquid chlorine?

    As long as you test and actually KNOW what you have and what you need in the pool, you can manage it any which way that works to keep the levels up. Around here we usually suggest that you keep your chemicals "separate", that is, add exactly as much CYA as you need, then add exactly as much chlorine as you need. But after you get real comfortable with the testing and the Pool Calculator and Effects of Adding Chemicals there and you are aware of the extras that come in various chemicals you can manage it all that way. You will want to keep good notes, however.
    You might decide to load 2 trichlor tablets a week in the autochlorinator and add bleach every other day after testing to determine volume needed. You might decide to use only bleach until CYA drops to 30 then use trichlor tablets for 2 weeks while you are out of town, then go back to only bleach until the CYA gets to 45 and then keep it at 45-60 for the heat of the summer. Or you could just use bleach for chlorine and use stabilizer separately for CYA.
    I keep a big chart that records test data and all chems added, what I was expecting and notes to myself. During the course of the year I will use mostly bleach, but occasionally trichlor tablets and occasionally cal-hypo powder. The tablets tend to mess with the TA levels and so making that switch can be good or bad, depending on where TA is at that point. As long as you know all the effects of your chemicals, it is OK. Just make notes and pay attention to all the test data. I run a full test each month so that the slower changing things, like TA and CH don't become an issue due to lack of attention when changing chemicals for some other reason.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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    Re: When and how often to add liquid chlorine?

    Thank guys for all the info. I've been reading and studying all the stuff on here for the last year. I must admit that last summer I used trichlor exclusively which is why the calcium is a little high and the CYA is a little high. I didn't get a test kit until a few months ago. I can't say why other than I'm cheap.
    I'm glad to hear that there isn't anything but chlorine and CYA with trichlor. (Why do they call it TRI-chlor if it only has two things in it? lol.) I can say that now I can monitor my water with a little confidence with my new found knowledge of pool chemicals, what and how they do what they do. I even end up getting into debates with the guys at Leslies. A few days ago the guy at the counter said there was no CYA in their Trichlor and that CYA goes away just like chlorine does. I educated him and I won the debate. He looked it up and finally gave in to my superior knowledge so he was unsuccessful at selling me some of his expensive chemicals. I felt vindicated. I'm no longer connected at the hip to the pool store. When I first got my pool, I was spending hundreds per month to keep it in shape according to Leslies. They loved me there.
    Now I go there maybe once a month or less to get chlorine when I'm too lazy to hit Walmart, Lowes or Home Depot.
    When I'm in the pool store and here what they are telling customers, it's all I can do to keep my mouth shut. I want to tell them they don't need that, they don't need the other thing either but I keep my mouth shut and cringe at how much they spend to keep things in the clear.
    Mesa Arizona. Old school 26,000 gallon in ground plaster pool with sand filter built in 1984.

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