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Thread: Pool eats chlorine - can't keep chlorine in pool.

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    Pool eats chlorine - can't keep chlorine in pool.

    We've been trying to use the BBB method this year, and I'm having some trouble with maintaining any chlorine in the pool. I put a large jug of chlorine (1.5 gal, I think) in this morning, which usually raises the level to about 4. It's 2:00 on a hazy, not particularly bright day, and the chlorine has already dropped to about .75. it'll be gone completely in a couple more hours. Why? Should I have to add chlorine every single day?? And, should the chlorine be dropping to zero every day??

    Pool color has been crystal clear, but today it is a tiny bit hazy. Can still see bottom easily, but doesn't sparkle like last week.

    I have a TF-100 kit that I'm learning to use. Here are results from this afternoon:

    FC .5
    TC .75
    pH 7.8, maybe a titch higher
    T/A 120
    CH 450
    CYA 70
    Temp 76 degrees F.
    24K In ground, vinyl lined pool. Sand filter.

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    Welcome to TFP.

    I suspect you have an algae bloom starting and you're barely keeping it at bay. You need to shock your pool. And remember that shock is a process and not just a product. Hold it at shock level until you pass the OCLT.

    And once you're done shocking, you will need to add chlorine every day.
    Dave J. TFP Moderator
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    Mod Squad jblizzle's Avatar
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    Welcome

    You got the best test kit ... so that is a VERY good start

    You need to review the Chlorine CYA Chart. For a CYA of 70ppm, you should NEVER let the FC get below 5ppm. Since this is obviously happening, you likely have something growing in the pool consuming the chlorine. So, you need to follow the Shocking Your Pool process until everything is cleaned up and then your FC use should go down.

    One note, your CYA is a bit high for a non-SWG pool. The Recommended Levels are a CYA of 30-50ppm. One option would be to replace water to lower the CYA level ... although 70ppm is not unmanageable.

    Here are some other links that may help from Pool School, while you may not have a green pool yet, there must be something in there somewhere:
    Defeating Algae
    Turning Your Green Swamp Back into a Sparkling Oasis
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    One thing I didn't add....because the pool was eating chlorine so fast, because the water has been clear, and because we weren't using it much (it has been at 64 degrees or so....) I've only been adding it chlorine a couple times a week. When I do add it, it quickly disappears...

    I don't know if that adds credibility to the algae hypothesis or not. But it does sound like shocking is the first time to try. What does it mean to "hold it at shock level until you pass the OCLT"??

    Thanks!
    24K In ground, vinyl lined pool. Sand filter.

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    It means not ot let it drop below shock level for very long and never let it get to zero. It's all explained in the links JB posted for you.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Pool eats chlorine - can't keep chlorine in pool.

    The pool Chlorine/CYA chart says shock level is 28 for a CYA of 70. Should I try to reduce my CYA before shocking the pool?? That is an enormous amount of chlorine!! The Pool Calculator says 11+ gallons...and at the rate this pool loses chlorine, seems like it would take a boatload more to maintain that level for any period of time.

    Any advice??
    24K In ground, vinyl lined pool. Sand filter.

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    Isaac-1's Avatar
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    If you are in an area where water is relatively cheap, you may want to do a partial refill (25-30%) to get your CYA levels down to the right range. That would put you in the right general range, if you live in the sunbelt you might want to keep it a little higher.

    Ike
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
    I use and endorse TFtestKits TF-100 from http://tftestkits.net
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    Mod Squad jblizzle's Avatar
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    Quote Originally Posted by diaperjoys
    That is an enormous amount of chlorine!! The Pool Calculator says 11+ gallons...and at the rate this pool loses chlorine, seems like it would take a boatload more to maintain that level for any period of time.
    That is the problem with high CYA, while the normal FC levels are not too bad, the shock levels get to be pretty high.

    Since your FC is disappearing rapidly, you are going to have to use a lot of bleach either way. The organics will consume the same amount of FC whether you had a lower CYA and lower shock level or a higher CYA with high shock level. The key is to stay ABOVE the shock level so that the algae is not multiplying while you are trying to kill it.

    It will take a lot to get up to 28ppm, but you will only need to add what is being consumed. Be sure to test hourly or so when you start to keep the FC level up.

    The water replacement is up to you ... can work either way. Just be sure to avoid any dichlor or trichlor in the future so that the CYA level does not go back up.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Am I doing this shock correctly?

    Ya'll advised me a couple days ago that my pool needed to be shocked. (It isn't holding chlorine, despite being very clear.) So, I began the process today. Below is a list of what I've done so far. Is it correct?

    CYA is 55, so I'm aiming for a FC reading of 20+ .

    9AM added 6.5 jugs of the 182 oz. size bleach (1.42 gal per jug), as per the Pool Calculator.
    10am FC = 30
    10:45 FC = 28, added 1 jug bleach
    1:23 FC = 24, added 1 jug bleach
    3:30 FC = 20 Added 1.5 jugs bleach
    5:00 FC = 22.5 Added 1 jug bleach

    Water remains clear. How long will this chlorine consumption continue? Days and days? I'm gone all day Friday, but I have Thursday free to monkey with the pool. I was hoping that since there is zero visible algae that this process wouldn't take too long. Should I add lots of extra bleach to "hold it" overnight without dipping below 20?? If so, how much?
    24K In ground, vinyl lined pool. Sand filter.

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    JasonLion's Avatar
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    Re: Am I doing this shock correctly?

    You appear to be doing everything correctly.

    Because you lose some chlorine during the day due to sunlight, daytime chlorine loss doesn't really tell us anything.

    You should do an overnight FC loss test to get a clear picture of how things are going, see the article in Pool School for instructions.

    Also, do you have a recent CC reading?
    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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    linen's Avatar
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    Re: Am I doing this shock correctly?

    JasonLion beat me, but here are my thoughts;

    Quote Originally Posted by diaperjoys
    Below is a list of what I've done so far. Is it correct?
    You are a little higher on FC, but since your pool is eating it fast you have no choice. For the overnight dose, it is safe to go up to the Mustard Algae Level for your cya level which is 32 ppm (from poolcalculator.com and 55 ppm cya). I would not go this high during the day unless you can't get back to the pool in time to generally stay above 20 ppm (you are really fine above 17 ppm, the FC shock level as calculated by the poolcalculator.com).
    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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    Re: Am I doing this shock correctly?

    I would brush and backwash tonight as well.
    16 x 32 15300 gal. IG Vinyl Jandy pump, Jandy sand filter, Paramount circulation system, Automatic pool cover.

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    linen's Avatar
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    Re: Am I doing this shock correctly?

    Quote Originally Posted by HoleInOne
    I would brush and backwash tonight as well.
    Brush yes, backwash when your pressure goes up 25% from your clean pressure.
    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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    Overnight FC - how does this sound?

    Still working on this shock process (first time trying the BBB shock methods...) How does this sound? Aiming for 20+ FC, based on a 55 CYA.

    5 pm - FC 22 (added 182oz bleach to help levels not drop too much overnight)

    5:30pm - FC 27, CC 0

    6:30 am - FC 13, CC .5 (brushed pool, added two jugs of 182oz bleach)

    10 am - FC 25, CC 0

    Pool continues to be clear, details on bottom of pool easily visible.

    How close to the finish line does this sound?? I have to be gone all day tomorrow, and I'm not sure how to set things up so I don't lose the ground we've gained so far. Any suggestions??
    24K In ground, vinyl lined pool. Sand filter.

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    JasonLion's Avatar
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    You seem to be moving along well, but still have one to three days to go.

    If you shock tonight and can bring the pool up to shock level tomorrow night things should be alright. If you miss then entire day there could be problems.
    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: Pool eats chlorine - can't keep chlorine in pool.

    Here's the current list of readings. Still losing chlorine at night. Once I do get the chlorine level stable, at, say at FC16 or so, isn't that much too high a level for safe swimming? What happens next? Do we just wait it out and wait for the chlorine level to drop down on its own?


    Day One
    9a – added 6.5 jugs bleach – 182oz ea. CYA 55
    10a – FC 30
    10:45a – FC 28 added 1 jug
    1:23p – FC 24 added 1 jug
    3:30p – FC 20 added 1.5 jug
    5:00p – FC 22 added 1 jug
    6:30p – FC 27 CC 0– last reading of the evening, sun hadn’t set, but all direct light was well off the pool

    Day Two
    6:30a FC 13 CC .5 total FC loss 14 points (12 hours), added 2 jugs
    10a FC 24 CC 0
    11:30 FC 19 CC 0 added 1 jug
    2:00 FC 19 CC 0
    3:30 added 1 jug
    6:30 FC 20 CC 0 added 1 jug
    8:30 FC 24 CC 0 – last reading of evening, after sundown

    Day Three
    6:15 FC 17 total FC loss 7 points (9 hrs, 45 min), added 1 jug
    mid morning – 1 jug
    mid afternoon – 1 jug
    9pm FC 18

    Day Four
    6:15 FC 15 total FC loss 2 points (9 hrs, 15 min), (pump was turned off overnight), added 1 jug
    8:30 – leaving for all day, added 1 large jug, 1 small jug
    9:15 pm – FC 18 CC 0

    Day Five
    6:45 FC 16 total FC loss 2 points (9 hrs, 30 minutes), CC 0, CYA 48
    24K In ground, vinyl lined pool. Sand filter.

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    Re: Pool eats chlorine - can't keep chlorine in pool.

    It is safe to swim at any FC up to Shock value. It will also come down to maintenance levels rather quickly but there is no need to wait unless you grossly overdose your pool. Looks like you are making nice progress....keep the faith!!
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    hawkeye's Avatar
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    Pool eats chlorine - can't keep chlorine in pool.

    You have to leave pump on 24/7 these little things will make or break you trust me.....I'd say cya is high, so that chlorine you think is enough really isn't.....effectiveness of chlorine goes hand in hand with stabilizer go off chart you already have its a no brainer

    18ft 52in deep doughboy 8000 gallons
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    Mod Squad Bama Rambler's Avatar
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    Re: Pool eats chlorine - can't keep chlorine in pool.

    The last little while in shocking can get frustrating but keep it up and you'll be done soon. You're making progress.
    Dave J. TFP Moderator
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