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Thread: Failing at Pool Math

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    Failing at Pool Math

    First thanks for all the great advice here. I have tried to do all my home work but am coming up short to try to get pool balanced- the water is clear but my readings are as follows:

    Salt- 1600 (test strip); 320 lbs of salt put in pool

    FC- 0
    FC at SWG output- 5
    TC at SWG output- 0
    PH- 7.4
    TA- 0
    CH- 130
    CYA- 0

    Apologies in advance if left anything out.
    Boston, MA- AG Intex 12,500 gallons vinyl, Cartridge filter, Intex 2500-Gallon Pump, Intex SWG CG-28669, Taylor K-2006 kit

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    Mod Squad JohnT's Avatar
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    Re: Failing at Pool Math

    Welcome to TFP!

    FC at SWG output- 5
    TC at SWG output- 0
    This isn't possible. TC is FC+CC, so TC can never be less than FC.

    With no CYA, your generator can't keep up with the sunlight consuming chlorine.

    Unless you've lost water and replaced, your salt level is in the 3100 range since you added enough salt to get there.

    You need to raise your CYA to the level recommended by Intex, and maintain your FC level by adding liquid chlorine or bleach until your SWCG can take over.
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    Mod Squad jblizzle's Avatar
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    Re: Failing at Pool Math

    Welcome to TFP!!!

    A TA of 0 and an pH of 7.4 is not a possible combination.

    Is this a fresh fill? You need to get the CYA up to around 70ppm for the SWG. And you should add 2ppm of FC with bleach ASAP.
    Jason, TFP Moderator
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    Re: Failing at Pool Math

    [EDIT] Typing same time as others [END-EDIT]

    Welcome to TFP!

    I see that you have a Taylor K-2006 test kit so that is good, but it's impossible to have a TA of 0 with a pH of 7.4. A TA of 0 means the sample turns red immediately instead of its normal green where you add drops to make it turn red. If it was red immediately, then the pH would be very low at 4.5 or lower. So something is wrong in the testing or the reagents.

    If your CYA is truly 0, then the UV in sunlight will break down chlorine quickly roughly half the FC broken down every hour and that is much too fast for the SWG to be able to keep up. So you need to add CYA into your pool by putting pure CYA into a sock and hanging it over a return flow or putting it into the skimmer (you can use an old T-shirt in the skimmer instead of a sock, if you prefer). If you put it in the skimmer, you need to have alternate suction flow to your pump such as floor drains or another skimmer or the skimmer needs a pipe below it into the pool as an alternate suction entry point (if you lift up the weir gate and feel suction in a pipe below the skimmer, then that's working OK).

    Finally, you report TC, but the K-2006 measures FC and CC which is what I think you meant (i.e. CC, not TC).
    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
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    Re: Failing at Pool Math

    Wow! So many nice folks here; let me correct my numbers and answer your questions

    FC- 0

    FC at SWG output- 5

    CC
    at SWG output- 0

    PH- 7.4

    TA- 90

    CH- 130

    CYA
    - (reagent and water never turned cloudy, thus I called that "0")


    This is a fresh fill/no water lost so salt strip must not be accurate
    Boston, MA- AG Intex 12,500 gallons vinyl, Cartridge filter, Intex 2500-Gallon Pump, Intex SWG CG-28669, Taylor K-2006 kit

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    Re: Failing at Pool Math

    So this is easy. You just need to get CYA aka stabilizer or conditioner into the water. It's one of the few things you buy from the pool store. For an SWG pool you normally want 80 ppm unless your pool doesn't get a lot of sun. You can use PoolMath to calculate dosing. If unsure, try to figure it out and then ask us. You'll add the CYA in a sock over a return flow or in the skimmer (or you can use an old T-shirt in the skimmer). If you use the skimmer, you need an alternate suction input so if you don't have a port below the skimmer that sucks when you close the weir gate to the skimmer, then don't use the skimmer for the CYA and instead hang over a return flow. Alternately, you can add CYA into the skimmer (without sock or shirt) to have it dissolve in the filter, but that can take up to a week and I think you should get CYA into the pool faster.
    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: Failing at Pool Math

    The sock has splashed down. Stay tuned and thanks!
    Boston, MA- AG Intex 12,500 gallons vinyl, Cartridge filter, Intex 2500-Gallon Pump, Intex SWG CG-28669, Taylor K-2006 kit

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    Re: Failing at Pool Math

    FC= 2.5

    CYA =40

    Adding more stabilizer and running SWG longer. Should I add some chlorine tabs to give it a boost or just stay the course? Thanks!
    Boston, MA- AG Intex 12,500 gallons vinyl, Cartridge filter, Intex 2500-Gallon Pump, Intex SWG CG-28669, Taylor K-2006 kit

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    Mod Squad jblizzle's Avatar
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    Re: Failing at Pool Math

    If you have the tablets, you could use them to help slowly build up the CYA, but you are going to want to get it raised to help the SWG out.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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