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Thread: Opening In-ground pool with SWG - best way to SLAM?

  1. Back To Top    #1

    Join Date
    Apr 2015
    Mississauga, ON, Canada

    Opening In-ground pool with SWG - best way to SLAM?

    Hi everyone,

    The pool is 51,000 Litres, salt with SWG, Sand filter.

    This is my second year with the pool, last time I used a "opening kit" specific to salt-pools with sand filters.
    it contained
    - 3x 1 lb packs of "Salt shock" - according to their website, each pack treats 30,000L
    - 1x 1 lb pack of "Oxy Salt"
    - 2x 1 lb packs of "Salt Revise"

    From the reading I've been doing on pool school, I'd like do away with the opening kit this year, and open using TFPC method
    The pool has been closed with a safety cover since October, and I expect it will be very dark green when opening (it was last year).

    Last year, the opening kit with "Salt shock" worked well, but I don't have any information on what the expected FC rise was , other than that "each pack treats 30,000L", and I used three of them.

    To SLAM at opening time - I'm thinking I should bring the FC 28, since my target CYA would be 70 (from the SLAM chart)
    I can use the pool calculator to determine quantity of bleach/liquid chlorine/Dichlor as needed, using a starting point of FC 0.0.

    Some things I'm unsure of
    - What would I expect the pool CYA levels to be at when opening in this situation? (still closed and can't test yet)
    - Assuming the CYA is low, should I add CYA to the green pool along with chlorine at opening time? Or just use chlorine to kill the green, vacuum, then use CYA?
    - To SLAM - would I be better to use bleach/liquid chlorine or Dichlor since it will also raise my CYA.

    Thanks everyone, I'm happy to be understanding what's happening in the pool, versus using things like "Revise/Soft/etc"


  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Opening In-ground pool with SWG - best way to SLAM?

    Welcome to TFP!

    You want to do a full set of tests after you have been able to run the pump for an hour. Don't make any assumptions about what your levels will be.

    If CYA is below 30, raise CYA to 30. Adjust PH to 7.2 to 7.4. Then start SLAMing.

    You never want to SLAM with dichlor. It adds CYA extremely quickly and makes your target FC level a moving target, which gets very confusing.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  3. Back To Top    #3

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    Kiss4aFrog's Avatar
    Join Date
    May 2013
    Hudson, WI

    Re: Opening In-ground pool with SWG - best way to SLAM?

    +1 with Jason.
    32K IG Vinyl, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added. 76
    275gal Conway Emerald Spa, bromine floater, indoor
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  4. Back To Top    #4

    Join Date
    Apr 2015
    Mississauga, ON, Canada

    Re: Opening In-ground pool with SWG - best way to SLAM?

    Thanks for the information!

    Is the idea of running the pump for an hour to ensure that i'm not just testing snow melt/ rainwater at the top of the pool?
    Since the pool water is so green - would I just run on recirculate as to not clog up the sand?

    I've seen information noting to vacuum to waste to get rid of the majority of the debris - is this recommended before or after SLAMing?

    Thanks again

  5. Back To Top    #5
    Patrick_B's Avatar
    Join Date
    Jun 2011
    Midland TX

    Re: Opening In-ground pool with SWG - best way to SLAM?

    Before SLAMing.

    Welcome to the forum!

    If you have heavy/large debris, you need to remove all you can BEFORE you vac or pump to waste manually. Using a leaf rake or whatever to get all you can out of the pool before SLAM. You want the hour run time to ensure you are well mixed before testing.

    Do you have a proper kit to perform a SLAM? You can't do it without a certain Chlorine kit. Let us know, and we can help you out.
    TFP Moderator
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    ABC's Of Pool Chemistry, Test Kits, SLAM Your Pool
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