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Thread: Shock help

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    Shock help

    Hi everyone! Thanks for all the knowledgable information I have found so far and for all the future advice
    I bought a house with in-ground pool 23k gallons. I shock the pool for the first time on Tuesday (2 days ago).
    I have been testing everyday. My ph is at 8.2 and FC 14.
    I checked today and pH still 8.2 and FC 11.
    I have read only time will lower the FC. I've also read that chlorine neutralizers can help.
    How long till the levels normalize?
    Any suggestions?
    Thanks again

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    JasonLion's Avatar
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    Re: Shock help

    Welcome to TFP!

    You need to lower the PH back into range (7.5 to 7.8) with acid.

    FC will come down over time. There probably isn't any reason to hurry it along. When the water is cold it can take a while, but they if the water is cold you probably won't be swimming so it shouldn't be a problem.

    Do you know your other levels, especially CYA? Having reliable test results from a top test kit is by far the best way to keep everything perfect and avoid problems.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Mod Squad woodyp's Avatar
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    Re: Shock help

    We're gonna need a full set of test results to offer you advice. Yes............FC will fall on it's own--no neutralizer required. Your PH will read artificially high with FC over 10. Welcome to the forum and enjoy Pool School.
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    Re: Shock help

    Hi! Thanks for the warm welcome!
    ph 8.2
    fc 11.5
    ta 150
    cya 50
    I have the tk-100 test kit (gift)
    I wanted to lower pH but am hesitant about adding more chemical to pool until FC lower than 5? Or is that nonsense?
    Thanks again

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    Re: Shock help

    With FC at 11.5, the PH will tend to read a bit higher than actual, but will still be close enough to be useful. Don't lower the PH too much, as it probably is a bit lower than that. But PH at 8.2 is certainly too high even with the possible test error. Lowering PH to around 7.7 to 7.8 should be fine.

    You don't want to adjust the PH when FC is above 15, as that FC level will throw off the PH test too much to be able to make reliable changes. You also don't want to be adjusting levels unless you have to when in the middle of SLAMing the pool. Other than that, there is no reason to not adjust levels as needed regardless of the FC level.

    The only thing that jumps out as a problem with your test results is your PH. You never want to let the PH go above 8.0.
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    Mod Squad tim5055's Avatar
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    Re: Shock help

    Poll
    Quote Originally Posted by fishoutofh20 View Post
    Hi! Thanks for the warm welcome!
    ph 8.2
    fc 11.5
    ta 150
    cya 50
    I have the tk-100 test kit (gift)
    I wanted to lower pH but am hesitant about adding more chemical to pool until FC lower than 5? Or is that nonsense?
    Thanks again
    Dont worry about the FC level at this point, add acid to get the pH down. For your CYA of 50 you never want the FC below 4 and a good target to,try to keep,it at is 6. With 6, if you loose some to UV during the day you are still above 4.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Shock help

    Please refer to the chlorine/CYA chart in Pool School. A CYA of 50ppm, your target FC should be 6. If you go to far under 5, you'll invite algae.
    I'd bet you my bikini you'll never get TFP water from a pool store!

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    Re: Shock help

    Thanks so much for the advise.
    I will definitely add acid to bring down my pH. I was looking at the chart at pool school.
    I was originally targeting 3...I'll change my target numbers.
    Is it safe to use the pool once my pH down if FC level is higher than 6? Been reading mixed reviews... Yikes!
    So many knowledgeable members, thank you again

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    JasonLion's Avatar
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    Re: Shock help

    Swimming is fine as long as FC is below shock level for your CYA level and at or above the minimum, PH is generally in range, you can clearly see the bottom of the pool, and there is no visible algae.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Shock help

    Ok so let me see if I am reading the chart correctly.
    The NON-SWG Pools:
    My current CYA = 50 and my NEW target FC is now 6. The shock FC of 20... that means my FC level has to be lower than that to use the pool, correct (you can see my newbie shock status showing...)

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    JasonLion's Avatar
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    Re: Shock help

    Yep, FC between 4 and 19 is swimmable when CYA is 50.
    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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    Re: Shock help

    Wow! I was reading all kinds of material saying not to swim unless FC = 5 or less.
    That could be the whole support for only time will lower FC.
    Made me wonder if recovery takes so long, who would shock weekly?
    Thank you for clarifying the chart for me. Its nice to know I'm in the right direction after being turned around...

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    Re: Shock help

    Should I remove my chlorine tablet floater since my FC high from shock? Again mixed reviews...advise?

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    Re: Shock help

    .
    Quote Originally Posted by fishoutofh20 View Post
    Wow! I was reading all kinds of material saying not to swim unless FC = 5 or less.
    That could be the whole support for only time will lower FC.
    Made me wonder if recovery takes so long, who would shock weekly?
    Thank you for clarifying the chart for me. Its nice to know I'm in the right direction after being turned around...
    Quote Originally Posted by fishoutofh20 View Post
    Should I remove my chlorine tablet floater since my FC high from shock? Again mixed reviews...advise?
    The basis of our method of pool care is to never shock your pool. Keeping the proper level of FC based on your CYA will keep the pool free from all the bad stuff.

    Remember, the tabs in the floater are slowly adding CYA, the higher the CYA the more chlorine you need. Most of,us use a salt water chlorine generator or liquid chlorine to,keep,the CYA where we want it.

    All of our methods are described in the Pool School with a link at the top of every page.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Shock help

    Quote Originally Posted by fishoutofh20 View Post
    Wow! I was reading all kinds of material saying not to swim unless FC = 5 or less.
    That could be the whole support for only time will lower FC.
    Made me wonder if recovery takes so long, who would shock weekly?
    The don't swim above FC of 5 rule is from before CYA was understood. CYA lowers the active chlorine level, changing the rule completely. The pool industry has been very slow to acknowledge this change despite the science being well understood for decades now.

    There is no point in shocking weekly if you are taking care of the pool properly. The shock weekly thing is based on the assumption that you completely ignore the pool during the week and let the FC level get way too low. It is much simpler and less expensive to spend a couple of minutes a day every day taking care of the water, at which point shocking weekly becomes a waste of time/money.
    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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    Re: Shock help

    I completely agree with the logic of daily maintenance. Which I was doing previously. It was "suggested" to me to shock the pool after having guests over.
    I will be testing the water again today and enjoying the pool this weekend. This experience shocking literally did that to me...
    Thanks again for everyones advice

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    Mod Squad tim5055's Avatar
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    Re: Shock help

    Quote Originally Posted by fishoutofh20 View Post
    I completely agree with the logic of daily maintenance. Which I was doing previously. It was "suggested" to me to shock the pool after having guests over.
    I will be testing the water again today and enjoying the pool this weekend. This experience shocking literally did that to me...
    Thanks again for everyones advice
    having guests or a pool party will increase your chlorine demand, but does not require a "shock".

    Just test the water and add only what your pool needs, no more.

    You can also be proactive and raise your FC a little before the party to keep it from dropping below your minimum.

    Ever notice that the folks suggesting you shock your pool are the folks selling you the shock?

    Your CYA is getting a little high unless you have a salt pool (I didn't see it listed), probably because of your use of a tab floater.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Shock help

    Yes the fear that some people instill to push products is sad. I thought the pool was good even after the guests left. All my numbers were within range.
    Which now I realize may have been low. I was trying to be at a CYA of 30 and FC 3-5.
    Thank you all for enlightening me on the basics. I read so much material it was hard to decipher it all.
    So I have adjusted my target numbers with all the wonderful advise for CYA=50 (which it is) and FC 4-6.
    I'm thinking I'll remove my floater to get my CYA steady...

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    Mod Squad tim5055's Avatar
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    Re: Shock help

    When you first take control of your pool it can seem like you are drinking from a fire hose with all the information rushing at you. Plus, the differing opinions you find do nothing to help with the confusion.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Shock help

    Very very true... but I'm so happy with all the support and information and patience you all have given me. Thanks again.
    I am happy to report:
    ph = 7.5
    FC = 10
    CYA =40
    So you know where youll find me today ... cause isnt that what its all about, the work we put into our pools to enjoy it

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