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Thread: Why fc so high?

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    Question Why fc so high?

    Am new to the forum, but just want to know why the experts on here recommend higher fc levels than any of the pamphlets or other materials I've read. Not being critical, but just want to know the reasoning.

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    Texas Splash's Avatar
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    Re: Why fc so high?

    Hello and welcome! This question is common, and we can get real technical, but the short answer is that much of the pool industry fails to recognize the relationship between FC and CYA (stabilizer). Please see the Pool School - Chlorine / CYA Chart. They work together to promote not only efficient chlorine effectiveness and protection, but also to make it safe for pool occupants. That's the very short answer. You can expect some others as well. Have a great day, and welcome!
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    Re: Why fc so high?

    As with many things, when something is postulated often enough, most people will assume that it must be right. Such is the case with the commonly-stated "advice" of maintaining FC of between 1 and 3 ppm. This has resulted in great frustration by pool owners who suddenly wake up to a green pool despite (in their minds) of having "adequate" FC.

    In actuality, the level of FC is determined according to the CYA level. CYA acts as a buffer from chlorine and protects it from being consumed too quickly by sunlight. It does this by holding some of the FC in reserve which lowers the effective strength of the FC . The higher your CYA level, the more FC you need to use to get the same sanitizing effect. The FC/CYA Chart chart outlines the recommended FC levels.
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    Re: Why fc so high?

    Ok, what is the best way to test cya? I have taylor 2005 test kit, and tested twice this morning. My average was 40 (45+35)/2. When I went to Leslie's they said it was 60. Went to another pool place to have it tested earlier in the spring and it was 57. Have added about 10lbs of 65% dichlor and use the pool regularly...I tend to think my reading is more accurate?

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    Texas Splash's Avatar
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    Re: Why fc so high?

    Your readings will always be more accurate. We always advise testing outdoors in natural sunlight, with the sun at your back. Keep the tube at waist level as you add the mixed solution and try to view the black dot. You are correct to be concerned in that many of those pool store products have a huge impact on raising CYA levels. It's good you are checking now before it gets too high.

    - - - Updated - - -

    That's another reason we emphasize the use of regular liquid bleach because it sanitizes without adding harmful additives or other chemicals. When we want CYA, we add stabilizer - simple.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Re: Why fc so high?

    If you keep adding dichlor to your pool you will increase the CYA in your pool very quickly. Once your CYA gets much above 60 you will start to have issues with algae, cloudiness, and just a general PITA to manage that pool. I would waste no time in getting a better test kit, either the TF-100 or add the Taylor FAS/DPD reagents so you can accurately test your FC/CC. I would also stop going to the pool store because the advice they give is completely incompatible with the methods used on TFP.

    Typically, all we use is bleach, muriatic acid, stabilizer, baking soda, borax and rarely soda ash. You can get this stuff, very cheaply I might add, at any big box store.
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    Re: Why fc so high?

    Quote Originally Posted by parkespapa View Post
    Am new to the forum, but just want to know why the experts on here recommend higher fc levels than any of the pamphlets or other materials I've read. Not being critical, but just want to know the reasoning.
    I haven't done the math, but I think that is probably not a correct assumption. While pamphlets claim that a pool should be held at 1-3 ppm, for some reason, they never factor in the "shock" that is performed at least once every week to prevent algae bloom. I suspect that they use as much chlorine as we do, if not more. Yet, not only have they have found a way to not include all of the chlorine they use, they tend to not even measure the ppm of the shock.

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    Re: Why fc so high?

    Thanks for all the great responses!

    I posted my problem in another thread, so I wont repost it here, and I need to get to the store to get more bleach.

    One more quick question if anyone knows. The Kroger 9% bleach I buy has a best before date. Any ideas on the difference between the manufacture date and the best before date?

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    Mod Squad zea3's Avatar
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    Re: Why fc so high?

    I would go by the manufacturer date to determine how fresh it is. I don't know what criteria they use to determine a "best by" date.
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    Re: Why fc so high?

    I guess you didn't understand my question...There is no manufacture date on the bottle, only a best before date. I only thought someone might know the answer, but I guess I could try to contact the manufacturer.

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    Re: Why fc so high?

    Personally, I would consider a "best before" date to be useless.... at least, for bleach. This link may help:

    http://www.troublefreepool.com/threa...asure-Strength

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    Re: Why fc so high?

    Quote Originally Posted by ewkearns View Post
    Personally, I would consider a "best before" date to be useless.... at least, for bleach. This link may help:

    http://www.troublefreepool.com/threa...asure-Strength
    Thanks

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