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Thread: Recommended CYA level

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    Recommended CYA level

    20,000 Gallon IG Vinyl
    Greater Boston Mass climate
    pool receives full sun dawn to dusk
    I have Ben's PS233 kit and stay on top of PH and TA.

    I have been practicing Borax and Baking Soda successfully for years, but used TriChlor 3" pucks in the skimmer for daily sanitizing and liquid 12% shock for shocking. While we never got nasty algae, it seemed there was always some showing on nooks and crannies of the steps and laddder. I think we under-sanitized, believing the OTO test that 1% or 1.5% was adequate when it wasn't.

    This year we're going to try straight Bleach for daily sanitizing with a constant CYA that doesn't creep up as the season progresses (which we got from TriChlor).

    My basic question is what CYA level would be recommended for a pool receiving full sun dawn-to-dusk in the moderate climate of greater Boston MA (daily high temps usually low-mid 80s)? I plan to add bleach each evening so it can do its thing overnight before the sun gets to it the following day... but what CYA level would afford decent protection through the day before that evening's next addition of more bleach?

    I'm thinking 30% to 40% CYA, but the full-sun issue has given me pause that maybe I should run a bit higher, so I thought I'd ask others.

    Once I have set my CYA, I'm fine with monitoring bleach dosage to keep above minimum CH levels for my chosen CYA level while still providing enough CH for daily sanitizing.

    Greater Boston area
    20,000 Gal IG Vinyl
    48 sq ft DE panel filter
    1 HP Hayward Pump
    Full Sun exposure all day

  2. Back To Top    #2
    frustratedpoolmom's Avatar
    Join Date
    May 2007
    SWSuburban Chicago, IL

    Re: Recommended CYA level

    If you target 50ppm CYA to start, backwashing your DE filter will cause it to drop slowly over the course of the season. You should be fine with a level of 50.
    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
    Perfectly Clear Pool Service, Find me on Facebook!

  3. Back To Top    #3
    cubbybeave08's Avatar
    Join Date
    Feb 2008
    Northwest Indiana

    Re: Recommended CYA level

    I get sun from 9 am to 6-6:30 pm...depending on what month it is. I have been keeping my CYA at 40 ppm. It seems to do just fine. Last year I targeted my FC to be at 3-5 ppm. This year I am following the pool calc guidelines and that should be 4 to 7 ppm. So I am adding about 30 to 50 ounces of 10 % bleach each night...This seems to work ok for me I have yet to have any kind of algae or other problems. You should be fine between 40 and 50 ppm. I would not go too much higher than that.
    Aqua Leader 24ft Round AG Wil-Bar Influence w/54 inch walls 13,500 gallons
    Swimline J-Blue Opal Liner, 1 4X20 Fafco Solar Bear Solar Heater
    Hayward 2 HP Swim Pro Voyager Pump Micro 150 with 4 way timer
    Swim Pro Voyager Filtration System with Hayward ABS Pearl wide mouth skimmer

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