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Thread: CYA Question

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    CYA Question

    Hi Everyone,

    I tested my CYA last night and there appears to be a dramatic decrease, I started over 100, got to 96 and last night I tested at 60; I had a wild couple of days (see my previous thread) and did 2 small drains and refills, could that have lowered it this much already? Does testing at night affect the scores? You keep putting drops in until black dot is completely gone, correct?

    Also, how do you know if you are losing too much water (like a leak) or if it is from kids swimming/evaporation/etc?

    Thank everyone!
    17x34 and ranges in depth from 3 ft to 6 ft.; I think 20-22 thousand Gallons
    IG -Vinyl with Waterfall
    Hayward Super Pump 1.5 HP
    Pentair DE 60 Filter
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    Patrick_B's Avatar
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    Re: CYA Question

    Depending on a few things loss of 1/4"-3/8" is not unusual. Yes light affects the Cya test, but if it's bright indirect light, the number ought to be pretty good. Try to test in, or mimic the suggested lighting which is direct Sun, at your back, test tube about waist high.
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    Re: CYA Question

    For a leak you can do the evaporation test. Fill a bucket and mark your line, same for the pool and take a measurement of the loss of each of 24-48-72hrs. The results should mimic each other.

    Depending on your definition of a small drain and refill the CYA could effectively have reduced by a good margin.
    18' x 36' vinyl steel wall pool with deep end, 2 lights and 6' steps, main drain, SWG, Cartridge Filter, 320,000 BTU Rheem heater, 3/4HP 1 stage pump - Ontario, Canada

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    Mod Squad tim5055's Avatar
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    Re: CYA Question

    Quote Originally Posted by AdamS View Post
    You keep putting drops in until black dot is completely gone, correct?
    It appears everything was answered but this....

    Yes, you slowly add the solution to the viewing tube until the black dot just goes away. The trick I learned here it to thne pour it back from the viewing tube into the mixing bottle and do it again. I generally do it three or four time to make sure I'm getting a consistent reading.

    As a matter of fact, I did it this week to discover my CYA was now down to 40. I may even turn of the Stenner Pump and dust off the tab floaters for a week out of town I have coming up.
    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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    JasonLion's Avatar
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    Re: CYA Question

    Doing the CYA test in artificial light will result in the test reading mistakenly high. Indirect sunlight is important for the test to be correct. The brighter light makes it easier to see the black dot, meaning you fill the tube to a higher level, and thus get a lower reading. The test is calibrated for indirect sunlight and will give incorrect results in artificial light.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    BoDarville's Avatar
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    Re: CYA Question

    Quote Originally Posted by tim5055
    Yes, you slowly add the solution to the viewing tube until the black dot just goes away. The trick I learned here it to thne pour it back from the viewing tube into the mixing bottle and do it again. I generally do it three or four time to make sure I'm getting a consistent reading.
    I do the same thing.

    The CYA test is the most subjective test in the lot. Here are more detailed instruction on how to perform this test properly:Extended Test Kit Directions See post #8.

    Quote Originally Posted by JasonLion
    Doing the CYA test in artificial light will result in the test reading mistakenly high.
    For the benefit of everyone reading this thread, this statement is one of the reasons pool store testing is often inaccurate, especially the CYA test. Pool stores read this under artificial light. After I first joined TFP, I took a sample to a nearby pool store and had then run a full suite of tests, just for grins. Their CYA measurement was twice what mine was. Another reason we say to trust your own test results.
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    Re: CYA Question

    Quote Originally Posted by BoDarville View Post
    For the benefit of everyone reading this thread, this statement is one of the reasons pool store testing is often inaccurate, especially the CYA test. Pool stores read this under artificial light. After I first joined TFP, I took a sample to a nearby pool store and had then run a full suite of tests, just for grins. Their CYA measurement was twice what mine was. Another reason we say to trust your own test results.
    Funny, but when I purchased the house with a pool I went to two different pool stores. Both told me my CYA was between 80 - 90. I still remember the guy from the store where they like me (I bought a spa and my M5 from them) telling me in January that it was 95, he thought that a little high for the end of the winter.

    When I purchased my own test kit I discovered 200+
    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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    Re: CYA Question

    Thanks everyone; how often do you test your cya?

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    Patrick_B's Avatar
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    Re: CYA Question

    Not often unless you change out a large amount of water. I test a lot, so I'll test a few times in the front of the season, then maybe a few times more until close. Many test perhaps only three times. Start, middle, and end of season which really is enough in most cases.
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    Re: CYA Question

    How does topping off lost water effect CYA? Also does rain effect CYA? Thanks everyone...
    17x34 and ranges in depth from 3 ft to 6 ft.; I think 20-22 thousand Gallons
    IG -Vinyl with Waterfall
    Hayward Super Pump 1.5 HP
    Pentair DE 60 Filter
    Hayward H300 Heater; Taylor K-2006 Complete

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    Mod Squad tim5055's Avatar
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    Re: CYA Question

    It depends on how the water was lost. When water evaporates the CYA stays in the pool.

    But, splash out, the water that leave in your swimsuit, back-washing or any other occurrence that take the total water solution out of the pool reduces CYA
    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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