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Thread: Additive Salt (no SWG) messing with TC and FC numbers?

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    Additive Salt (no SWG) messing with TC and FC numbers?

    I'm at wits end on this one. I added salt to "soften" my water a bit (my hardness is off the charts, out of the tap it's 400+) and am currently holding steady around 2000ppm based on what my test kit is telling me (K2006 or something like that with the salt add on.)

    I CAN NOT get my cholorine levels down. I haven't added any pucks or liquid in 2 weeks, and my TC and FC are still way up above 10.

    Could this possibly be caused by the salt additive messing with the readings? I've tested cholorine with both the big test kit, 2 different small test kits, and strips, and I get the same reading.

    CYA is in the 40 range as I just refilled the pool a couple weeks ago. Maybe that's the issue? But, I would think the lower CYA would cause the chlorine to burn off? PH is 7.4 so that's within range.

    Only thing I can think is that the pool itself is generating cholorine from the salt?

    Not that I'm really complaining....the water is crystal clear, feels good to swim in, and no flora growth! I just don't want a surprise one day to find the TC and FC at zero after being away for a couple days and have a mess on my hands!!

    Ideas?
    28K Gallon old-skool plaster hole in the back yard in desperate need of an acid wash and a fixed skimmer diverter (yes, it's still broken)
    Hayward SuperPumpVS pushing some giant hayward cartridge filter setup
    SharcVacXL and Zodiac G2 to keep things clean

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    Mod Squad pooldv's Avatar
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    Re: Additive Salt (no SWG) messing with TC and FC numbers?

    Do you have an FAS/DPD test? That will measure FC up to 50ppm. Then you will know what level it is and as long as it is below shock level for your CYA then it is safe to swim. FC will only drop 2-4 pppm per day, maybe a little more when it is high. Chlorine CYA Chart

    Here is the test by itself, TFTestkits.net FAS-DPD test

    Oh, and I'm nearly positive that your pool isn't turning your salt into chlorine!
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    Mod Squad jblizzle's Avatar
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    Re: Additive Salt (no SWG) messing with TC and FC numbers?

    Quote Originally Posted by pooldv View Post
    Oh, and I'm nearly positive that your pool isn't turning your salt into chlorine!
    Well, I am 100% positive it is not

    I agree without the FAS-DPD chlorine test, you are kind of flying blind.
    Jason, TFP Moderator
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    Re: Additive Salt (no SWG) messing with TC and FC numbers?

    LOL I didn't think it was making it's own chlorine either....if it is, I'm filing the patent tomorrow

    PoolDV - yes, I have the full K-2006 test kit which can do FAS-DPD (and I added the salt test to it) - I'll do it again tomorrow in sunlight and see what it says.

    At this rate, I'm just confused since I'm seeing NO burn-off. Pool (surface temp) is 74,ambient is 60 to 90 last couple of days. I've been testing close to daily and seeing no burn-off whatsoever.
    28K Gallon old-skool plaster hole in the back yard in desperate need of an acid wash and a fixed skimmer diverter (yes, it's still broken)
    Hayward SuperPumpVS pushing some giant hayward cartridge filter setup
    SharcVacXL and Zodiac G2 to keep things clean

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    Mod Squad jblizzle's Avatar
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    Re: Additive Salt (no SWG) messing with TC and FC numbers?

    No need to do the FAS-DPD in sunlight. In fact, I do all my testing (except the CYA) in the kitchen.

    - - - Updated - - -

    Oh, and use a 10ml water sample so each drop is 0.5ppm (not what the K-2006 has in the instructions).
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Mod Squad pooldv's Avatar
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    Re: Additive Salt (no SWG) messing with TC and FC numbers?

    You saying test in sunlight makes me think you are using a DPD chlorine test (hard to read shades of pink) with R0001 and R0002 drops and not an FAS-DPD test with 0870 powder to turn it pink and 0871 reagent drops to turn it clear.
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