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Thread: Do I need to increase CYA?

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    Join Date
    Sep 2007
    Location
    Toronto
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    106

    Do I need to increase CYA?

    I have a salt water fiberglass pool with a SWG and an automatic cover. We only use the pool for about 4 times a week, about 3 hours each time, otherwise the cover is closed. Here are the numbers:

    salt: 3200
    FC: 2
    TA: 100
    TH: 250
    PH: 7.5
    CYA: 20
    SWG setting: 20%

    So far the only problem was metal stains which were cleaned up by ascorbic acid treatment. The water is always sparkling. I was wondering if there is a need to increase CYA since most of the time the pool is not exposed to sunlight. I don't want to increase FC too much as it may promote metal stains.
    OH TWINS
    San Juan 8500 gal Fiberglass Pool, Sta-Rite Max-E 1 HP pump, Star-Rite System 3 Cartridge Filter 300 sq. ft,
    Sta-Rite Max-E 200,000 BTU gas heater, Aqua Logic SWG with P-4 panel. Goldline wireless remote control,
    3 Jandy Neverlube Valves with Goldline motorized control, iRobot Verro 500 pool cleaner
    5 Poolstar 1000 LED Lights, LED strip light at waterfall, Prozone Ozonator PZ7 with degasser column,
    Jandy Auto Waterfill, Aquamatic motorized pool cover, Poolbuster Max CC handheld vacuum.

  2. Back To Top    #2
    Guest

    Re: Do I need to increase CYA?

    If the pool is NOT an indoor pool it would be a good idea. You will have better pH stability because you will be able to turn your generator output down. See this thread:
    viewtopic.php?f=21&t=3663
    Also, calcium hardness levels ARE important for fiberglass. There is evidence that proper calcium levels can help prevent staining and cobalt spotting. I noticed that you did not list calcium hardness.

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    frustratedpoolmom's Avatar
    Join Date
    May 2007
    Location
    SWSuburban Chicago, IL
    Posts
    11,963

    Re: Do I need to increase CYA?

    Actually OP lists TH at 250...

    WIth an SWG, the recommended level for CYA is 70-80, but you should also check your manufacturers recommendation so that you don't void any warranty. See the article about recommended levels for SWG pools in Pool School... you can run your pool with a CYA of 70 and a FC of 3, at the minimum. As long as you keep your PH and TH in range, a FC of 3-5 is unlikely to stain your pool, but if your metals are high, consider a maintenance dose of metal sequesterant to help prevent staining.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  4. Back To Top    #4
    Guest

    Re: Do I need to increase CYA?

    Quote Originally Posted by frustratedpoolmom
    Actually OP lists TH at 250...
    Total hardness is a useless test for pools and indicates that the testing was done with strips. Strips cannot test calcium hardness, only total (calcium and magnesium) hardness. Calcium hardness numbers are still needed. Total hardness is going to read higher than calcium hardness and from the number posted I can pretty much be sure the CH is a bit too low. I stand by what I said before.

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    frustratedpoolmom's Avatar
    Join Date
    May 2007
    Location
    SWSuburban Chicago, IL
    Posts
    11,963

    Re: Do I need to increase CYA?

    Quote Originally Posted by waterbear
    Quote Originally Posted by frustratedpoolmom
    Actually OP lists TH at 250...
    Total hardness is a useless test for pools and indicates that the testing was done with strips. Strips cannot test calcium hardness, only total (calcium and magnesium) hardness. Calcium hardness numbers are still needed. Total hardness is going to read higher than calcium hardness and from the number posted I can pretty much be sure the CH is a bit too low. I stand by what I said before.
    That's what I get for skimming. My bad, I stand corrected.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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