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Thread: How much CYA should I buy?

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    jjwalker's Avatar
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    Aug 2012
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    How much CYA should I buy?

    So when I finish my build and start filling...in a few weeks...how much should I buy, assuming pool math is suggesting 80oz to get to 40?

    I can buy a 7lb or jump to 25lb...7lb will take care of the fill, but am I going to need a 25lb tub? how much will I need to add say over a year?
    18x36 vinyl / sport pool 5.5' deep / 1.5hp Tri-Star 2spd / Hayward c3030 325 sqft cartridge / ~15k gal / TF100

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    Re: How much CYA should I buy?

    Once you add the CYA, you won't need to add any more except to "top it off" because of splash out and backwash losses, etc. 25lbs will probably last you several years, unless you plan on draining and filling your pool up every season, etc. You can always buy a couple of stabilized chlorine tabs to top off your CYA, as well. I'd say go with the 7lbs, or maybe if you can find a 10 (I got a 10lb bucket at Leslie's back in the day). It'll always be available, as I believe it's a product from industrial waste.

    As far as how much you need, you can do the calculation this way. You said you need 7lbs for your pool. So, if you have 3 month swimming season, let's say you backwash weekly ~ 200 gallons. And lose another ~50 gallons to splashout, so 250 gallons per week for 12 weeks = 3000 gallons. The amount of CYA you'll need is 3000/15000 * 7 ~ 1.5 lbs per year. A 25 lb supply would last you about 10-12 years, if you don't drain and fill!

    Good luck!

    Take care,
    Mo
    Mo - 21K gal, IG plaster, dual Pentair SuperfloXF pumps, 72 sqft DE filter, cartridge filter for the spa, dual Waterco multi-cyclone prefilters, Dual Circupool SWGs, Polaris booster and cleaner, TBD custom controller.

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    jjwalker's Avatar
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    Re: How much CYA should I buy?

    ok, that's helpful. the jump in price was like $50 so I wanted to ask before I bought

    18x36 vinyl / sport pool 5.5' deep / 1.5hp Tri-Star 2spd / Hayward c3030 325 sqft cartridge / ~15k gal / TF100

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    Houston, Texas
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    Re: How much CYA should I buy?

    JJWalker - I would probably start off at CYA 30ppm and see how that works. The recommendation for vinyl pools is 30 - 50 ppm. I'm in Houston, which is similar to your location and I kept my CYA on the lower range so that my FC was lower as well. I didn't see a significant difference in CL burn off by the sun. but your results may vary. maybe try at 30 then see how long it takes to burn off, then try 40 ppm a few weeks later and see how long it takes then. A lower CYA means a lower shock level which means less bleach. My bather load was more than the sun, so it worked better for me to keep cya lower.
    36,000 gallon IG Gunite (40 x 20), 1.5 HP Hayward pump, Pentair Nautilus NS-48 DE filter, 2 skimmers, 12 - (2 x 20) Fafco Solar Panels (Goldline controller not hooked up yet), Hayward Swimpure Plus SWG, Blue Pearl Robot cleaner. New Dr. Wellness X-12 standalone Lifestyle Spa.

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    jjwalker's Avatar
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    Re: How much CYA should I buy?

    thanks mac, good advice. just ordered test kit and cya! thx
    18x36 vinyl / sport pool 5.5' deep / 1.5hp Tri-Star 2spd / Hayward c3030 325 sqft cartridge / ~15k gal / TF100

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    Mimi C.'s Avatar
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    Re: How much CYA should I buy?

    Quote Originally Posted by mfk0213 View Post
    back in the day when I still used CYA).

    so why don't you use CYA now?
    1990 IG 13K gal freeform gunite, PureLine Prime 2.7 HP Variable Speed Pump, Waterway ProClean 200 sf cartridge filter, attached spa with gas heater, waterfall with dedicated pump Dolphin Premier robotic cleaner, TFT-100, Florida with Pool Cage * Total Pool Newbie *

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    Re: How much CYA should I buy?

    I'm actually considering using it again. I updated the previous post to eliminate confusion.

    Good luck with your new pool - it is an exciting journey. If you follow the advice of the senior folks on here, you will undoubtedly have a much easier time thank I did!

    Take care,
    Mo
    Mo - 21K gal, IG plaster, dual Pentair SuperfloXF pumps, 72 sqft DE filter, cartridge filter for the spa, dual Waterco multi-cyclone prefilters, Dual Circupool SWGs, Polaris booster and cleaner, TBD custom controller.

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    Mimi C.'s Avatar
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    Re: How much CYA should I buy?

    Because we just bought a house with a pool. Total newbie.
    1990 IG 13K gal freeform gunite, PureLine Prime 2.7 HP Variable Speed Pump, Waterway ProClean 200 sf cartridge filter, attached spa with gas heater, waterfall with dedicated pump Dolphin Premier robotic cleaner, TFT-100, Florida with Pool Cage * Total Pool Newbie *

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    LFrankow's Avatar
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    Re: How much CYA should I buy?

    Quote Originally Posted by Mimi C. View Post
    Because we just bought a house with a pool. Total newbie.
    Then off to Pool School with you straight away.
    Ask away if you have any questions at all, we were all where you are now.
    Lou - 13.5K Gal pool, AG Intex 24 X 52"
    19" Sand Filter/1 hp pump, Aqua Trol SWG
    90 sq ft Homemade Solar panels + 80 sq ft Fafco panels, coupled with a SS heat exchanger/Hot Water Tank, Pentair SolarTouch, Taylor k-2006

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