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Thread: shocking with high CYA

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    shocking with high CYA

    So to follow up my old CYA thread, I'm doing incremental water replacement by pumping some water out to irrigate the lawn then replacing (dropping about 3" at a time from an approx 15 x 30 ft rectangle, then refilling with fresh water ... yes I know this will take a while but with water rationing in place I don't think we could do it in one shot). I've been aiming to keep the FC at around 10 but know there's some residual mustard algae because every morning when I brush the pool there are some light clouds of yellowish-brown dust and my FC has been dropping from 10 to around 7.5 overnight.

    I see from the FC/CYA chart that the recommended shock level for a CYA of 100 is 39 - now when the note at the bottom of the chart says " lower FC levels are often sufficient though they take longer to kill algae" what's a ballpark lower number that would probably work - say, 20-25 ppm? How long would I probably have to keep it at shock level to subdue the algae (and hopefully reduce the frequency at which I need to add a gallon of bleach to the pool?)

    For the past few days, I've been adding a gallon of 10% bleach every morning and it seems enough to keep the algae from increasing but not enough to kill it.
    1950's-era 17K gallon formerly fiberglass, newly replastered IG rectangle (~15x30'),
    Hayward S244S Sand Filter with Franklin Electric 0.75 HP motor and WhisperFlo WFE-3 pump
    Clear ThermaTex bubble cover
    Manual vacuum

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    Re: shocking with high CYA

    If you have yellow/mustard algae, then it takes an even higher shock level of around an FC that is 60% of the CYA level for an extended period of time, say around 3 days, to thoroughly kill this algae. You would also need to get behind light niches, under ladders, put in poles and nets and brushes that have been in the pool, wash your swimsuits, clean the pool cover, etc.

    All of this becomes pretty impractical with such a high CYA level so really you should dilute the water first to lower the CYA and then you can attack the yellow/mustard algae with full force to try and get rid of it.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: shocking with high CYA

    Since he can't replace all his water right now, would it be more practical to use a product like yellow treat and no mor problems to maintain a level of bromine to temporarily ignore his current high CYA problem until his water can be replace?
    -Kevin
    X-Pert Pool Service
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    22,000 gal / 16' x 32' / Vinyl / Hayward s244t /Pentair SuperFlo 1 hp

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    Re: shocking with high CYA

    That is certainly an option. Though clearly he's got to get the CYA lowered at some point and that is the preferred approach, if that can't be done then essentially turning the pool into a bromine pool temporarily is a workaround and that's what these sodium bromide products do.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: shocking with high CYA

    yeah, I know we've got to get the water replaced but with our current water allotment I don't think we can do more than the drain/water lawn and refill until later in the year when we don't need to water the landscaping.
    Is "Yellow Out" comparable to "Yellow Treat" (our nearest pool supply store is Leslie's and I've seen Yellow Out there but don't know if they carry Yellow Treat.

    PS Chem Geek, just noticed you're also in the SF Bay Area - any rec's for repair/resurfacing contractors? (Our pool has numerous bubbles/chips/flaked off areas so we know we'll have to bite the bullet and have some repair done in the very near future)
    1950's-era 17K gallon formerly fiberglass, newly replastered IG rectangle (~15x30'),
    Hayward S244S Sand Filter with Franklin Electric 0.75 HP motor and WhisperFlo WFE-3 pump
    Clear ThermaTex bubble cover
    Manual vacuum

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    Exeter, PA
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    Re: shocking with high CYA

    Yellow out is ammonia based so yellow treat and yellow out are not the same. Most of united chemicals products like yellow treat, green treat etc are sodium bromide based.
    -Kevin
    X-Pert Pool Service
    x-pertpool.com
    X-Pert Pool on Facebook and @XPertPoolServic on Twitter
    22,000 gal / 16' x 32' / Vinyl / Hayward s244t /Pentair SuperFlo 1 hp

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    Re: shocking with high CYA

    Quote Originally Posted by PoolCleanerMom
    PS Chem Geek, just noticed you're also in the SF Bay Area - any rec's for repair/resurfacing contractors? (Our pool has numerous bubbles/chips/flaked off areas so we know we'll have to bite the bullet and have some repair done in the very near future)
    Our original pool contractor was Janssen Pools and they did an excellent job, but they work in the North Bay so I'm not sure you could get them if you were further away in the Bay Area. I'm sure there are other competent contractors; I am just not familiar with them. Our pool was a mid-range in price; not high-end with rocks and waterfalls as shown in many examples on the website.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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