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Thread: Trying to SLAM but FC not rising

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    Trying to SLAM but FC not rising

    I'm SLAMing and am concerned I will add too much CYA because I've read it takes a while to show up.

    Pool is pretty green.

    Test kit K2006
    FC 1.0
    CC 2.0
    pH 7.4
    TA 80
    CH 500
    CYA appears 0 (it is not even 30 and that is the lowest number on my test kit).
    I added enough CYA two days ago to supposedly raise it to 30 but it is not showing up yet. I didn't do the sock method as I hadn't read that part yet (doh!).

    I've read I am supposed to proceed with the SLAM as if the CYA is there. The calculator is directing me to add about 128oz each time I check the FC, but that doesn't seem to raise FC by more than 0.5 at a time. It seems that I should be adding a lot more chlorine to get to the recommended 10FC.

    Please advise what you would do. Many thanks.

    18,000 GL, IG, plaster, cartridge, Starite pump
    Last edited by danvillepool2014; 06-13-2014 at 10:13 PM. Reason: footer needed

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    Casey's Avatar
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    Re: Trying to SLAM but FC not rising

    Welcome Danville.

    Do you have an inground or an above ground pool? If you could put your pool specs in your signature, it would help.

    Ok... We need to SLAM to the level you raised your CYA and just assume it's in there. So how much did you raise it to? A CYA of 30 will require a SLAM of 12pm. Plug it into Pool Math. Add the chlorine and check it within a half hour to see if it's holding. If it's not holding, you add more to bring it back up to 12 and keep dosing the pool until it holds. Doing it at night will take the sun out of the equation and help you hold an FC reading at least a little longer than in the day time as 2 things consume FC and that is sunlight and organics.

    Post back any questions.
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    Re: Trying to SLAM but FC not rising

    Thanks!

    How many days does it usually take for CYA to show up?

    Best site ever, by the way.

    18,000 GL, IG, plaster, cartridge, Starite pump

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    Casey's Avatar
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    Re: Trying to SLAM but FC not rising

    It takes about a week.

    Use settings below the Pool School button, top right of every page to save your signature.
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    Re: Trying to SLAM but FC not rising

    Did you recently fill or are you just opening and found your CYA to be low?
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    Re: Trying to SLAM but FC not rising

    Just opening and found it to be low. Why does that make a difference? (Just trying to learn as much as I can, thanks).
    18,000 GL, IG, plaster, cartridge, Starite pump

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    Casey's Avatar
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    Re: Trying to SLAM but FC not rising

    Do you remember what your CYA level was last year by any chance?
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

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    Re: Trying to SLAM but FC not rising

    Last year I remember it got super high from shocking that the pool store told me to do. I think it got to about 100 before I realized my error. I haven't drained but have filled a little here and there since then. How would it come down so low without draining it? Thanks.
    18,000 GL, IG, plaster, cartridge, Starite pump

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    Re: Trying to SLAM but FC not rising

    Isn't this where Richard320 usually posts the picture of a Clorox tanker truck ?

    OK, so one *possibility* is that the CYA got converted to ammonia over the winter by bacteria. If so then (a) you don't want to add any more CYA than you have in case it gets converted too, and (b) each time you add bleach it's going to get used up almost immediately attacking the ammonia, and IIRC the total amount of bleach required until FC starts to go up will be roughly the same as the CYA level you had last fall. If that is the case, then you'll need to add 12 ppm worth of bleach ~8 times before the FC starts going up and the bleach starts working on algae rather than ammonia.

    The good news is that whether you have ammonia or not, your actions are exactly the same at this point... keep adding enough bleach to get to 12ppm, check FC level after running the pump for 1/2 hr to 1 hr, and add more bleach if needed. At some point the FC will start to go up, and at that point your pool will start getting less green.

    EDIT -- for what it's worth, when I asked PoolMath how much 8.25% bleach I needed to raise an 18,000 gallon pool from 0 ppm FC to 12 ppm FC it told me 326 oz, or 2-1/2 gallons of bleach. Sounds like you are seeing something different -- can you check your numbers ?
    Cedar hot tub, 680 US gallons - Snorkel wood-burning heater, canoe paddle, "offline" Intex 1000 GPH pump/filter with skimmer

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    Re: Trying to SLAM but FC not rising

    BTW I don't know if it is possible to bypass the filter on your system but until your FC level starts to hold I would think about running the pump with the filter bypassed so you don't load up your cartridge with an infinite amount of algae.
    Cedar hot tub, 680 US gallons - Snorkel wood-burning heater, canoe paddle, "offline" Intex 1000 GPH pump/filter with skimmer

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    Re: Trying to SLAM but FC not rising

    That is super helpful. I'll get a ton of bleach this weekend and an ammonia testing kit and will report back.

    You are right that my numbers were off. I am using 10% bleach so I should have stated that PoolMath directs me to add about A COUPLE of 128oz jugs at a time. Thanks again.

    - - - Updated - - -

    I don't think there is a way to bypass the filter but I could remove the cartridges temporarily I suppose. But isn't it inevitable that I get stuck with a ton of algae in the cartridges anyway? Or does the SLAM sort of change the algae to some form that doesn't clog up the cartridges? Really appreciate all the advice.
    18,000 GL, IG, plaster, cartridge, Starite pump

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    Re: Trying to SLAM but FC not rising

    You're absolutely right that you are going to have to filter it out anyways. I was just thinking that at the moment algae is still growing and will keep doing that until you can keep the FC level up, so bypassing the filter now would let you concentrate the annoying filter/clean/filter/clean/filter/clean phase into a smaller number of days. I have a cheapo pump/filter that I have to take apart if I want to clean the filter -- I don't know if you have to do that or if there is some "move the handle to position B and flush all the gunk out" option.

    But yeah, one way or another you are going to have to filter it out.

    Another thing to consider would be putting a knee-high stocking or something over the skimmer basket to help catch algae before it gets to the cartridge. You'll need to check it frequently but might be easier to clean than your cartridge -- all depends on your specific equipment I guess.
    Cedar hot tub, 680 US gallons - Snorkel wood-burning heater, canoe paddle, "offline" Intex 1000 GPH pump/filter with skimmer

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    Re: Trying to SLAM but FC not rising

    In an ammonia slam you can test and dose as often as every 30 min. Once your CL starts to hold ( 6 ppm) go to hour intervals. Keep assuming 30 on the cya and target 12 for the CL.


    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
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    Re: Trying to SLAM but FC not rising

    I was suspecting ammonia too. You should hold off with the CYA and kill the ammonia off first. You should hit the pool very hard, fast and consistently through out the day with the bleach. You will need that tanker truck of bleach because the ammonia will use up a lot of it! Please do post the ammonia test results. Sounds like your pool had a party this winter and now it's pretty sick. Ain't nothing good ole bleach can't handle!
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    Re: Trying to SLAM but FC not rising

    Do you know if removing the filters and continuing to run the pump would do any damage to the equipment? My filter is an old Pentair CC520P and it looks like the one attached (not the exact model but very close).filter.jpg
    18,000 GL, IG, plaster, cartridge, Starite pump

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    Re: Trying to SLAM but FC not rising

    It won't hurt anything. It will just turn the filter housing into a big fat section of pipe.
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    Re: Trying to SLAM but FC not rising

    Here's the results from my ammonia test and SLAM:

    10:30AM
    Ammonia - 8PPM
    FC 0.5
    CC 1.0
    ADDED 8 JUGS OF 10% BLEACH AT 128 OZ EA

    12pm
    Ammonia somewhere between 4-8PPM (not a precise test kit)
    FC 2.5
    CC 1.5
    ADDED 11 JUGS OF 10% BLEACH AT 128 OZ EA

    12:45pm
    Ammonia 0.25
    FC 5
    CC 0.5
    ADDED 1 JUG OF 10% BLEACH AT 128 OZ EA

    1:40PM
    Ammonia 0.25
    FC 6
    CC 0.5
    ADDED 4 JUGS OF 10% BLEACH AT 128 OZ EA

    2:40PM
    Ammonia 0.25
    FC 20
    CC less than 1

    Pool smells awful and looks blue. I have been keeping the cover closed in between tests all day. Would opening it help the scent improve and lower the FC quicker? Thanks.
    18,000 GL, IG, plaster, cartridge, Starite pump

  18. Back To Top    #18

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    Trying to SLAM but FC not rising

    It looks like you turned the corner on the ammonia. Now for the algae.
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
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    Re: Trying to SLAM but FC not rising

    Leave the cover off. You want the pool to outgas any oxidized junk during the SLAM.
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  20. Back To Top    #20

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    Re: Trying to SLAM but FC not rising

    Do I need to add anything else to combat the algae or is it just a matter of filtering it out? Thanks.
    18,000 GL, IG, plaster, cartridge, Starite pump

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