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Thread: Need to Shock

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    Need to Shock

    FC 6
    CC .5
    PH 7.5
    TA 110
    CH 250
    CYA 70-80

    Pool is in full sun 9-8. I add bleach every night usually FC is between 5.5- 7 so i use calculator to figure up to around 9. It takes any where from gallon up. My cc is always .5 I have some gray stuff in the skimmer don't know if it's from bathers, lotion etc. or algae. Wondering if I need to shock is that a lot of bleach to add every night or is it because of sun and high CYA? Thanks for any help.. Maybe I should do a overnight FC lost test. What do you all think?
    16X32 Rectangular In Ground Built 1998, New Vinyl liner and Motor 8/2012, 19,000, Hayward Sand Filter, Hayward Super Pump,PoolPilot DIG-220 SWG, 2 Skimmers, Main Drain, Clean Machine Robot, Full Sun, Bleach, TFTest Kit
    Central, VA

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    Re: Need to Shock

    The overnight FC loss test will let you know if there is organics in your water. I agree that's what I would do first.
    32x16 ft Grecian rectangular vinyl pool 8ft on deep end - 19000 gal. 18" Hayward S-240 sand filter. 250K BTU Pentair MasterTemp heater. Hayward 3/4 HP Super Pump.

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    Mod Squad Bama Rambler's Avatar
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    Re: Need to Shock

    I'd recommend doing the overnight test then shock if you need to.

    Get a couple of scum balls too. They'll catch most of the stuff you're talking about. It's probably from the swimmers.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    svenpup's Avatar
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    Re: Need to Shock

    The question of what is "normal" FC loss has come up a lot lately. 3ppm per day is not excessive. You could do an overnight FC loss test to get a better idea of where the FC demand is coming from and whether you need to shock.
    TFP Method Advanced Intermediate
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    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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    Re: Need to Shock

    If the CYA were truly 70-80 ppm, then the typical chlorine loss starting from 9 ppm FC would be roughly 2 ppm FC while you are seeing a drop of 2 to 3.5 ppm. Though this is still plausible, it does seem a little on the high side (unless you have very high bather load, especially if people are peeing in the pool). The gray stuff in your skimmer may be a sign of excessive organic load in your pool. I presume you have backwashed your sand filter recently and seen dirty outflows turn to clear. You might want to inspect the filter just in case there is clumping with channeling -- that can happen from biofilms though they normally don't form unless the chlorine was too low at some point in time.

    As others have noted, a test of the overnight drop in FC would help you determine whether you should shock and/or look for organic contaminants in your pool (i.e. checking the filter, skimmer, pump basket, etc.).
    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: Need to Shock

    Thanks for the input i've been running my robot and not backwashing since the pressure never changes. I guess I need to backwash and do an overnight loss thanks. Oh what is a scum ball?
    16X32 Rectangular In Ground Built 1998, New Vinyl liner and Motor 8/2012, 19,000, Hayward Sand Filter, Hayward Super Pump,PoolPilot DIG-220 SWG, 2 Skimmers, Main Drain, Clean Machine Robot, Full Sun, Bleach, TFTest Kit
    Central, VA

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    JasonLion's Avatar
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    Re: Need to Shock

    A scum ball is a ball made out of a special foam material. You put it in your skimmer and it soaks up any oils, suntan lotion, tanning oil, etc that get into the skimmer. They can be handy if you have oil accumulating inside the skimmer.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    poolgirl22's Avatar
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    Re: Need to Shock

    Can these be cut in half and still be effective?
    I just got some (oooohhh 33% bigger now!) and it is a bit too big for the skimmer...the lid keeps it in one place.
    Plus I'm cheap, err, thrifty, and I like to get the most for my money...Seems like there's a lot of space that doesn't get used.
    Backyard pool-less, but used to be.....
    16,100 gallon, 18x38 3.5 ft deep oval AG, Vinyl, Sand, 1hp pump
    http://www.poolservicestech.com Liquidator
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    JasonLion's Avatar
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    Re: Need to Shock

    Sure you can cut them up.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  10. Back To Top    #10

    Re: Need to Shock

    FC 8 after adding bleach and checking 45 min. later. But this morning checked it was FC 9. Guess I need to check again tonight and wait longer after adding the bleach. I also need to back wash at least once a week even know I'm using the robot? I guess just the amount of sun my pool receives and the high CYA is the reason I need to add so much Bleach every night. Next year there will be no pucks or sticks used in the pool and hopefully I can keep the CYA down some. But with high sun exposure do you need to keep CYA at the higher end? thanks again for the input. This site is great!!!!!
    16X32 Rectangular In Ground Built 1998, New Vinyl liner and Motor 8/2012, 19,000, Hayward Sand Filter, Hayward Super Pump,PoolPilot DIG-220 SWG, 2 Skimmers, Main Drain, Clean Machine Robot, Full Sun, Bleach, TFTest Kit
    Central, VA

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