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Thread: CYA Very High and Algae Continually Difficult to Eradicate

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    Join Date
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    CYA Very High and Algae Continually Difficult to Eradicate

    I have a 33,000 gallon inground pool w/pebble tech finish...first time I've had a high cya level...don't know for sure why...I use liquid chlorine, shock, and tablets. I'm not sure which tablets are best: trichlor or dichlor; maybe you can help me. I realize I am going to have to drain part of the water out of the pool. Is there any other way since our state is in a terrible drought?
    I have a 33,000 gallon pool that has a pebble tech finish a Pentair Clear Filter and an energysaving pump and heater. cya reading is high. I use liquid chlorine, shock, and tablets. Should my tablets be trichlor or dichlor and how can I tell which is which?

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    Re: CYA Very High and Algae Continually Difficult to Eradicate

    How did you get your results? What are the numbers?

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    Beens's Avatar
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    Re: CYA Very High and Algae Continually Difficult to Eradicate

    The shock (if powder rather than liquid) and tablets added that cya for you. Dichlor and trichlor both add almost as much cya as they do chlorine. The chlorine is consumed and needs to be replenished. The cya sticks around unless you replace water to lower it.

    That's why TFP strongly recommends using only liquid liquid chlorine for regular maintenance. (it won't add anything extra but a small amount of salt)
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Re: CYA Very High and Algae Continually Difficult to Eradicate

    Thank you, I think I've finally learned this lesson. Would I stlll shock my pool once a week as recommended with the powder form (is there a liquid form of shock)? So TFP recommends just liquid chlorine for even the shock?

    - - - Updated - - -

    By using my regular little test kit. The CYA was over 100 but the test tube only measured to 100, it was past that. My chlorine and pH were right on, but now I've learned that the CYA locks in the chlorine and does not let it attack the algae; therefore, algae stays, grows etc.
    I am emptying a portion of my pool as we speak
    I have a 33,000 gallon pool that has a pebble tech finish a Pentair Clear Filter and an energysaving pump and heater. cya reading is high. I use liquid chlorine, shock, and tablets. Should my tablets be trichlor or dichlor and how can I tell which is which?

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    Fort Lauderdale, FL
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    Re: CYA Very High and Algae Continually Difficult to Eradicate

    TFP method does not recommend a weekly shock. It is not necessary if you maintain chlorine levels properly. If you ever had a reason to shock the pool, TFP advised to SLAM (shock level and maintain) until you pass a set of criteria.

    Weekly shocking is the pool store answer to hold algae at bay when FC is too low for your CYA level. It's a short term band-aid at best, but since most powdered "shock" adds CYA, the problem is compounded.
    15k in-ground plaster, Hayward C900 cartridge, 3/4hp single speed pump, Barracuda G2 cleaner, TF-100

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