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Thread: Do I need to find chlorine breakpoint?

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    Do I need to find chlorine breakpoint?

    I had mild staining to my vinyl liner 4 weeks ago. I rubbed a spot with a lemon and it went away.

    I reduced chlorine to almost 0 and did a vitamin C treatment. Worked great. All stains went away. Per instructions I waited 4 days to shock. In that time massive algae bloom occurred. I did 2 green & clean treatments (which entailed raising PH to 8.0 then super chlorinate ) this failed over 1 week period. Also added non copper algaecide... To no avail. Deep green pool.

    I shocked the pool with 12 lbs of 73% calcium hypo and 5 lbs of dichlor. This started to work. Started to clear. Now just grey and cloudy. I replaced the cartridge filter with a new one and added clarifier. For the last 5 days pool staying grey and cloudy.

    Continue to shock with 99% sodium dichlor w/ 55% active chlorine. 4lbs per day. Still grey and cloudy.
    FC goes to 5ppm+ then goes to 0 over night.

    Readings:
    FC 0-5+ppm
    TC 2-5ppm
    CC 1-0ppm
    PH 7.3
    Alk 90
    CYA 30
    Phosphates 0
    Temp 85

    4 weeks in with a green/grey pool. I have put another 10 lbs of dichlor in last 24 hrs and FC again dropping. I would appreciate any thoughts on chlorine breaking point or other strategy.
    Many thanks!!
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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    JasonLion's Avatar
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    Re: Do I need to find chlorine breakpoint?

    Welcome to TFP!

    You really need to stop adding all those different chemicals, most of which have some significant negative side effects. Dichlor is the worst, as it add huge amounts of CYA to the water, and will rapidly drive your CYA level too high.

    Breakpoint is a myth, it doesn't mean anything.

    The key to getting control over your pool is reliable test results. That means having your own top test kit (TF100 or K-2006). While you are working on getting that, do some reading in Pool School (button on the top right of every page).
    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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    Charlie_R's Avatar
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    Re: Do I need to find chlorine breakpoint?

    welcome to TFP!

    Chlorine "breakpoint" is a myth.

    With all the dichlor you have poured into your pool, I am seriously doubting the CYA of 30.

    Your numbers look like test strips. Are they?

    Your best bet for clearing an algae loaded pool is to first get a very good test kit. Strips and pool store testing are notoriously inaccurate. You can get either the TF-100 or the Taylor K-2006. Of those, I would strongly suggest the TF-100, with the XL option. You can get either at http://TFtestkits.net

    We here at TFP can help you get your pool clear of all algae, but there are a few things you will need to do:

    Start with the ABC's of water chemistry -- http://www.troublefreepool.com/conte...ater-chemistry

    Next, read about how to clear your pool -- http://www.troublefreepool.com/conte...tain-shockingl

    There are many more articles in pool School, but you should start with those.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    Re: Do I need to find chlorine breakpoint?

    Reading up. Testing from 3 sources: 1) my Taylor DPD test kit; 2) pool store water testing; 3) test strips
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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    Re: Do I need to find chlorine breakpoint?

    Poolboy6

    It's very likely that you are going to have to SLAM your pool. You might want to read up on the SLAM process and start thinking about where you can get LOTS of liquid chlorine from (Costco, Sam's Club, Walmart, local hardware store, etc). You're going to need a lot so try to research prices, volume and concentrations (6%, 8.25%, 10% and 12% are most common).




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    Mod Squad jblizzle's Avatar
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    Re: Do I need to find chlorine breakpoint?

    Quote Originally Posted by Poolboy6 View Post
    Reading up. Testing from 3 sources: 1) my Taylor DPD test kit; 2) pool store water testing; 3) test strips
    Which one is right?

    None are capable of measuring the high FC levels needed for the SLAM process.
    Jason, TFP Moderator
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  7. Back To Top    #7

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    Re: Do I need to find chlorine breakpoint?

    Hello All—since the last post I stopped adding dichlor and added 2 gallons of 8.25% of bleach every night. Using my old Taylor tester each night FC would be ~5ppm and each morning it would be ~1ppm.
    In that time it started to slowly clear. I can now see the deep end bottom. Hosing cartridge filters daily. I received the TF-100 in the mail today. Readings:

    CYA=100
    PH=7.5
    FC=6.5
    CC=1
    TC=7.5
    Calcium=500
    Alkalinity=100

    Continue slamming?
    I would think I can add a clarifier at this point to get rid of the remaining cloudiness??
    I would appreciate ant recommendations on sustaining FC levels and reducing CYA.
    Thanks All!!
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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    Mod Squad jblizzle's Avatar
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    Re: Do I need to find chlorine breakpoint?

    Your CYA is way too high, only way to lower that is though water replacement. This should be the first step.

    With cloudy water and a high CC number, you need to follow the ShockLevelAndMAINTAIN Process.

    We do not recommend using any clarifier ... especially when you have not even started to SLAM.
    Jason, TFP Moderator
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    Re: Do I need to find chlorine breakpoint?

    Recommendation on how much water to drain?
    And As I am still SLAMMING should I wait...or drain and fill simultaneously while slamming and keep filter running?
    Thanks.
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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    Mod Squad jblizzle's Avatar
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    Re: Do I need to find chlorine breakpoint?

    Depend on how high the CYA really is. Do the dilution version of the test.
    You can not drain more than leaving at least a foot of water in your shallow end without risking the liner shifting.
    Drain 50% (or down to 2 foot in shallow end), refill, recirculate, retest, re-drain if needed.
    Jason, TFP Moderator
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    Re: Do I need to find chlorine breakpoint?

    What Jason said, with a liner pool you risk the liner lifting, and wrinkling (or worse) if you get below about a foot of water in the shallow end. The CYA test is really only good up to about 100 ppm, anything higher tends to read as 100. You could dilute 50/50 with CYA free tap water and multiply your results by two, but there is really no point since you will still be limited by how much you can drain on a liner pool, so my vote is do a partial drain, refill, mix and then retest.

    Ike

    p.s. for non SWG pools we suggest a CYA level of no more than 50 ppm for most pools unless it is located in an extreme sunbelt location.
    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
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    Re: Do I need to find chlorine breakpoint?

    Thanks Ike. To be clear should I drain NOW or wait to finish the SLAM?
    Readings presently are:
    Cya=100
    FC 4.5
    CC 1
    ALK 90
    Cal 425
    PH 7.5
    I can see the bottom. Lightly cloudy. Algae dust shows when I brush.
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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    Mod Squad jblizzle's Avatar
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    Re: Do I need to find chlorine breakpoint?

    Lower CYA, then SLAM.
    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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  14. Back To Top    #14

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    Re: Do I need to find chlorine breakpoint?

    Ok. Drained off and refilled. Present readings are:
    CYA=75
    PH=7.5
    FC=3
    CC=0.5
    Calcium=375
    Alkalinity=70

    Should I drain and fill again or is this manageable? And if manageable how many gallons of 8.25% to achieve the FC/Shock FC of 8/28 per the SLAM chart.
    Thanks
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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    Mod Squad tim5055's Avatar
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    Re: Do I need to find chlorine breakpoint?

    You should probably drain & refill more. 75 CYA is still high. It is going to take a lot of bleach to SLAM with your CYA that high.

    In your spare time you should be reading the Pool School (link at the top of every page). It is a great community here, but we do ask that you read and try to understand the information being taught. Questions are always welcome and folks will try to direct you and teach you the methods.

    The goal is for you to acquire the information to care for your pool.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Mod Squad jblizzle's Avatar
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    Re: Do I need to find chlorine breakpoint?

    Use PoolMath to calculate dosages.
    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: Do I need to find chlorine breakpoint?

    Thanks Tim and Jason!
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

  18. Back To Top    #18

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    Re: Do I need to find chlorine breakpoint?

    Update: drained and filled again. Getting ready to SLAM. Present readings:
    FC - 2.5
    CC- 0.5
    PH - 7.5
    TA - 60
    CH - 300
    CYA - 50

    CC is already at 0.5--do I need to SLAM regardless of OCLT?
    This is my first time SLAMMING so please let me know if this looks correct. Using Pool Math and SLAM Chart:
    Add 581 oz (or 4.8 gallons) of 8.25% bleach to get to a FC Shock Value of 20ppm and do OCLT.
    For the OCLT am I looking for a 19ppm the next morning?
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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    Mod Squad jblizzle's Avatar
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    Re: Do I need to find chlorine breakpoint?

    There is no reason to do the OCLT until your water is crystal clear and you have no more than a CC of 0.5ppm.
    For the OCLT you need to test at least 30 minutes after you last chlorine addition and then do not want to lose more than 1ppm by the morning test.

    Realize that the 8.25% bleach bottles are 121oz so not a full gallon.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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  20. Back To Top    #20

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    Re: Do I need to find chlorine breakpoint?

    OK. So 2 questions:

    1)CC is already at 0.5. Do I even need to SLAM? (water is clear NOT Crystal; minor algae dust during brush)

    2) IF YES, then I add 581 oz to achieve a Shock FC of 20 ppm, I am done if 1) water crystal and CC is 0.5 or less; OR 2) OCLT is less than 1ppm. so if I SLAM tonight to achieve 20 ppm; a 19ppm the next morning would be an acceptable OCLT. Correct?

    I am not sure if I am reading the SLAM directions correctly or not. Thanks.
    22,000 vinyl IG 18x36
    Hayward Star Clear II cartridge filter; 100 sq ft
    Pentair 320 chlorinator 3" Tabs
    Pentair 1 HP motor

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