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Thread: Disappearing CYA

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    Disappearing CYA

    hi there - been a member for 2 years or so - did the pool school - bought the tf-100 test kit or whatever it is.

    I use liquid chlorine and have had pretty good success the last 2 years.

    Now my question, is my CYA levels. I live in Florida with intense heat all day 90 degrees + and complete sunlight all day and it rains pretty much every day - no screen. I just cut a tree down which gives my pool about 8 hours more sunlight. I have had trouble keeping my CYA up to a normal 30-50 level. I've heard some people do even higher for Florida pools maybe 50-70. I've had issues in the past where I've had CYA way to high and had to refill because my chlorine was ineffective. So now I'm cautious with it. BUT now i cant keep the levels at a reasonable amount - it literally will get to 40-50 and within two weeks be 10 or zero. I'm going through tons of the stuff. I've tried super shocking to off-the-chart levels to kill any ammonia or whatever it is that helps the CYA not breakdown as fast. I'll have a 30 CYA and a 5-7 FC 0 CC test and then a week later, 0 FC and 0 CYA.

    Maybe its just the intense weather making my pool hard to keep up wtih? I havent had any problems with algae (yet) but i've gone through a frog infested green swamp before. Any suggestions? I cant find any posts on fast dissappearing CYA - some people only deal with it a few times a season if that.
    TEST KIT: Taylor Technologies K-2006C

    POOL: 33,000 gal 20'x40' IGP, Vinyl, 1.5 HP Two Stage Pump Motor, 340 sq.ft. Jandy CL340 Cartridge Filter, Jandy Aqua Pure PLC1400 SWG, Polaris 280, AquaLink RS By Jandy Control Center with Jandy PDA Model #8265

    JACUZZI: 320 gal Caldera Spa Paradise Series Martinique with OEM Aqua Sun Zone - XL-30AE Ozonator

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    JasonLion's Avatar
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    Re: Disappearing CYA

    That sounds like there is a lot of water replacement going on. This most often happens when there is an autofill system masking a leak. It is also remotely possible to lose CYA if FC has fallen to zero for at least a day, though that is way less likely.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  3. Back To Top    #3

    Re: Disappearing CYA

    I don't have an auto-fill system and I just re-piped my pool pump a few months ago. I have little to no air leaks. I'm wondering if i'm just not adding enough CYA - i don't actually know a good way to add it other than throwing a sock in and waiting a day or two. Maybe I'm just not putting enough in and getting an inaccurate reading. I use the test tube-black dot thing so its somewhat subjective.

    We do get a ton of rain - sometimes my pool will get an inch or two of rain a week then slowly evaporate, etc.

    If i am truly at zero or low (5, 10etc), i'll have to get formula to see how much to add. I know too much means drain & refill and I've been there twice. And I know too little doesn't do anything and i go through a billion gallons of chlorine. I just did the calculator and it says to add 50-60 oz of stabilizer. I usually will only add a big tube-sock full. I've never added that much at one time so maybe i'm not losing it, maybe i just never had any.

    I know its best to add it increments as to not over do it - How long should i wait to measure? a day or two?
    TEST KIT: Taylor Technologies K-2006C

    POOL: 33,000 gal 20'x40' IGP, Vinyl, 1.5 HP Two Stage Pump Motor, 340 sq.ft. Jandy CL340 Cartridge Filter, Jandy Aqua Pure PLC1400 SWG, Polaris 280, AquaLink RS By Jandy Control Center with Jandy PDA Model #8265

    JACUZZI: 320 gal Caldera Spa Paradise Series Martinique with OEM Aqua Sun Zone - XL-30AE Ozonator

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    Join Date
    May 2012
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    Toronto, ON
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    Re: Disappearing CYA

    If you figure out what is going please keep us posted - I am having the same problem although I live in a different climate region - see this thread: http://www.troublefreepool.com/threa...-would-this-be
    Vinyl 18'x36' in-ground 100,000 L, Jandy Aquapure 1400 SWCG, Jandy Lite2 heater, StaRite System3 filter, Evac tube solar heating panels

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    BoDarville's Avatar
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    Jun 2012
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    Re: Disappearing CYA

    Quote Originally Posted by ke263565
    How long should i wait to measure? a day or two?
    I would wait about a week after a CYA addition before re-testing it. However from a chlorine dosing standpoint, I would adjust the FC dosage according to the targeted CYA level 24 hours after adding the CYA. For example, let's say you started with a CYA of 30 ppm and you added an additional amount of CYA to reach a target level of 40 ppm. After 24 hours of adding the CYA, adjust your FC dosage as though the pool is at a CYA of 40 ppm. But still wait a week before retesting CYA.

    After ruling out a leak/autofill situation, the testing process may be the cause of the fluctuation you are seeing. The CYA test is the most subjective of the tests that we recommend. I would suggest looking at post # 8 in this thread which provides additional instructions on CYA testing: Extended Test Kit Directions. Since lighting is critical when doing this test, one of the things that has worked well for me is that I always perform this test in the late-morning to early-afternoon hours on a bright sunny day so that the lighting level is consistent. I always get consistent results.
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