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Thread: Breakpoint chlorine level?

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    Breakpoint chlorine level?

    I opened the cover 3 days ago. Pool was black. Tested the water 0 Cl pH 7.5, CYA 0. Added dichlor 78% to raise Cl to 13. After the first hour dropped down to 0 again. Bumped it back up and now it is 18 and holding with a 2.5 CC level. The water is still really brown. I have vacumed to waste twice; brushed the sides religiously and still have the high Cl reading. The high Cl reading has me bugged. I can't figure that out. Have I not hit the threshold for the algae? Here are my most current readings: Cl 18, CC 2.5, pH 7.5, TA 80, CYA 0; CH 500. I know I need to replace 50% of the water to lower CH. My question is should I go ahead and replace water or bump up the Cl level to the breakpoint first?
    Scott
    1) 24000 gal
    2) DE filter
    3) IG
    4) plaster
    5) 1 hp

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    Mod Squad Bama Rambler's Avatar
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    Re: Breakpoint chlorine level?

    Breakpoint chlorination is a myth. It doesn't work like that.

    You need to shock and keep it at shock until you pass the OCLT. Your CC's are still high which says you're still killing stuff in the water.
    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: Breakpoint chlorine level?

    thanks for the response. So, I don't need to add more Cl? Just let it continue at present levels?
    Scott
    1) 24000 gal
    2) DE filter
    3) IG
    4) plaster
    5) 1 hp

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    Re: Breakpoint chlorine level?

    Don't worry about the CH right now. Keep shocking until your CC is 0.5 or less, your water is clear, and your FC holds to within 1 ppm of loss or less overnight.

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    Mod Squad Bama Rambler's Avatar
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    Re: Breakpoint chlorine level?

    Since you have zero CYA your shock level is 10 ppm FC. You need to keep it at that level until you pass the OCLT.
    If you really have zero CYA then you'll lose all your FC during the day. It's easier to shock if you add about 30 ppm CYA to the water while you're doing it.
    How are you testing?
    Do you have iron in your water?
    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: Breakpoint chlorine level?

    That's the thing. I haven't lost any of the chlorine since day one. This morning my Cl was 15 and CC 3. I do not know if I have iron
    Scott
    1) 24000 gal
    2) DE filter
    3) IG
    4) plaster
    5) 1 hp

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    Mod Squad Bama Rambler's Avatar
    Join Date
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    Re: Breakpoint chlorine level?

    I suspect that your CYA number is wrong. That it's a lot higher than you think.
    How are you getting those numbers?
    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: Breakpoint chlorine level?

    I use my TFP kit to get the numbers.
    Scott
    1) 24000 gal
    2) DE filter
    3) IG
    4) plaster
    5) 1 hp

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