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Thread: Total Chlorine Guideline

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    Join Date
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    Question Total Chlorine Guideline

    As a new spa owner, I am climbing the learning curve of water chemistry. One quick question: When I check the TC level daily (using the OTO test in the TF-100 kit), is there an ideal target range that I should be aware of for a SWG spa? I could not find any such reference in the TF-100 kit. Thank you kindly.

    Kit
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    Texas Splash's Avatar
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    Re: Total Chlorine Guideline

    Kit, here's a quote from the SPA "sticky" post thread:
    Sanitation
    On a fresh fill use Dichlor until you get to 20-30 ppm CYA. (10 ppm FC = 9 ppm CYA)
    Then switch to Clorox Unscented 6% bleach.
    Never let FC drop to Zero for any length of time. Keep it between 3-6 ppm normally, min of 1 ppm, and shock to 12 ppm once a week.
    Use MPS if needed before hot tub party's and/or once a week to help oxidation. Don't use more than needed, because it's acidic and may lower your TA/pH.
    Dichlor, Bleach and MPS is all you need to keep your tub sanitized.
    Use PoolMath to calculate exact amounts to add.
    Here's the entire thread: How do I use Chlorine in my Spa (or pool)?).
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  3. Back To Top    #3

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    Re: Total Chlorine Guideline

    Texas,

    I am a bit confused with the "sticky" since I have a SWG spa. The liquid chlorine does not seem to be applicable.

    However, I think that my question was a bit premature. I apologize for that. Allow me to provide some quick background & rephrase my concern. My in-ground, SWG, plaster spa was filled for the first time about 45 days ago. The pool contractor should be here next week to add salt & turn on the Pentair IntelliChlor SWG. In the meantime, I have periodically added liquid chlorine for sanitation. At this point, my CYA measures 0. If I understand correctly, I need to first add CYA & establish a level of 70 - 80. Then I can target the FC to the level of CYA. Am I correct?

    Would it be advisable to add CYA now or wait until I add salt & the SWG is running? Sorry for any confusion. I am trying to process a lot of new information.

    Kit
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    Texas Splash's Avatar
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    Re: Total Chlorine Guideline

    EDITED:

    Kit, I wasn't totally comfortable with my last post. Instead, I'm posting a comment from one of our resident spa experts (Chemgeek) who has this to say about a spa with an SWG:
    Most SWG systems are undersized and for outdoor pools need a higher CYA to be able to limit chlorine losses from sunlight so that the SWG is able to keep up. Also, minimizing the needed SWG on-time reduces the rate of pH rise that is also a problem in most SWG pools. This is why the SWG chart shows a limited and higher CYA range.

    Spas are very different if they have covers. They aren't as susceptible to algae since their covers keep out most light and when the spas are run hot (towards 104F) algae is inhibited. In a spa, bather load is much, much higher than in a pool so most chlorine is added right after a soak to handle bather waste so the FC level generally gets quite high soon after a soak. Since most people want to soak with a low level of chlorine in a spa to minimize noticing its effects, the usual rule is to add enough chlorine after a soak so that one has 1-2 ppm FC at the start of their next soak. If one does not soak every day or two, then in between soaks one would usually target 2-4 ppm FC with 30-40 ppm CYA so the minimum most of the time would be roughly similar to the SWG minimum of an FC that is 5% of the CYA level, but this applies for manual dosing as well (again, because the spa is mostly covered, the water generally hotter, and the chlorine level often varying higher).

    Because of varying bather load and the slow response from an SWG, manual dosing of chlorine after a soak is usually still required unless it's just one person soaking for a shorter time and the SWG has a boost mode or there is an ozonator.

    If the spa is covered, then 30-40 ppm CYA is a good range to shoot for. This is similar to what is recommended for indoor pools though they can be 20-30 ppm CYA in order to more easily have a higher active chlorine level to help oxidize bather waste due to the lack of sunlight. In spas, the water is generally hotter and the bather loads generally have the FC be higher at times so a higher CYA level target of 30-40 ppm is usually better. We don't list spas and indoor pools in the chlorine/CYA chart because they are less common, and for spas as I wrote above it's more complicated but their maintenance is described in the Using Chlorine in a Spa "Further Reading" article in the Pool School.
    I hope this helps you and makes sense.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Join Date
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    Re: Total Chlorine Guideline

    Texas,

    Indeed, it is helpful. Thank you.

    Kit
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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