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Thread: Increasing CYA

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    Join Date
    Jul 2015
    Location
    Tampa, FL
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    18

    Increasing CYA

    Greetings All,

    Just finished a Pebble Tec remodel on the pool, and after the refill (city water) I'm looking at the following numbers: FC: 3 / PH 7.5 / TA: 90 / CYA: not registering. CYA before the remodel was always relatively high (80-90), so I'm in uncharted waters - pun intended - here. I guess I could just throw in a couple of chlorine pucks and wait for the inevitable increase, but the idea of dropping pucks into my pool bothers me for some reason. So here's my question(s): Is a CYA below 30 really bad? Do I just get over it and add the pucks, or is there alternate methods? If pucks are the answer, anyone have any idea on how many it will take to get me into the good (30-50?) zone? Thanks in advance for the recommendations!

    Wade
    10,000 Gallon Pebble Tec
    Hayward Star-Clear Plus C900 cartridge filter
    Hayward 1.5 HP pump
    Pool is filled from city water

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    Mod Squad JVTrain's Avatar
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    Feb 2014
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    Central Minnesota
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    Re: Increasing CYA

    Pool Math is your friend. Input your pool volume and it will let you know how much CYA you need to add to get to your target, if you're going with adding CYA, not pucks, which I would recommend. Use the sock method to add the CYA either in a skimmer or hang in front of a return. Don't assume your CYA is 0 though, it's just less than 20. Assuming it's 10-20 is safer when targeting your desired CYA.

    CYA below 30 is bad because you'll be wasting chlorine. With low CYA, sunlight will chew up your FC faster, especially in Florida. Are you using a SWG or manually chlorinating with bleach? If manually chlorinating, I would suggest your CYA at at least 40, 50 probably better. If SWG, then you're looking at the 70-80 ppm range.

    You can also use Pool Math to determine how much a single puck of trichlor would add in CYA but using the Effects of Adding Chemicals section at the bottom. Most trichlor pucks are 8 ounces in weight iirc.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    Richard320's Avatar
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    San Dimas, CA (LA County)
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    Re: Increasing CYA

    Tap water has zero CYA in it, so it's not surprising your test comes up empty.

    Pucks take too long to dissolve to rely on them alone to raise CYA. Using Effects of Adding Chemicals in poolmath... 5 lbs of trichlor will raise FC by 55 and CYA by 33. Assuming you could control the dissolving rate to keep it at 2 FC per day or so, it will take a month to bring CYA up. Trichlor is also very acidic, so you might find yourself actually low on pH and TA and then you'll need to add chemicals to fix that.

    On the other side.... One 4 lb canister of CYA granules should bring you up to 48 CYA in a matter of days. You'll lose a little due to splash out but you still have a little room to use pucks should you leave town for a week or so somewhere down the line. 60 CYA would not be excessive in Florida.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    borjis's Avatar
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    Re: Increasing CYA

    AS Joel pointed out you do need the CYA for sun protection. Indoor pools don't need cya.

    My pool is just slightly bigger than yours and 3 lbs of CYA made it 30 ppm
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
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  5. Back To Top    #5

    Join Date
    Jul 2015
    Location
    Tampa, FL
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    18

    Re: Increasing CYA

    Thanks to all for their responses and recommendations, I didn't consider that there might be such a thing as CYA granules. Problem solved...as always, the folks at the TPF forums rock!
    10,000 Gallon Pebble Tec
    Hayward Star-Clear Plus C900 cartridge filter
    Hayward 1.5 HP pump
    Pool is filled from city water

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