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Thread: Chlorine level question

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    Chlorine level question

    Hey everyone. Got a quick question regarding the chlorine level in our pool. I posted a few days ago with all of my levels and my chlorine level was a bit low, and the ph a little high. I added acid to adjust the ph, and cranked up the SWCG (POLARIS) to 5 hours a day. After testing this for chlorine this morning, i came up with this.
    FC 2.4
    CC 0

    So I think the FC is a bit high correct? But 0 Combined Chlorine? Do I need to adjust for this, and how would I with SWCG?
    Thanks
    16x32 IG vinyl, 19,000 gal, 1.0 hp pump, sand filter, 2 returns, 1 skimmer, diving board, slide

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    JasonLion's Avatar
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    With CYA of 30 and a SWG you should be able to have FC down to just above 1 and be alright. Having it closer to 2 adds a nice safety margin. Since you tested in the morning, I would say that your FC is reasonable. For a more telling measurement you should test in the early evening after a sunny day, when FC is typically lowest.

    CC of 0 is ideal. You want CC to be as low as possible, so zero is perfect.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. Back To Top    #3

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    Allright good deal. Thanks alot Jason.
    16x32 IG vinyl, 19,000 gal, 1.0 hp pump, sand filter, 2 returns, 1 skimmer, diving board, slide

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    Would the level of FC desired in a saltwater pool (assuming the ideal CYA level) vary depending on the run time of the chlorine generator? In other words, would the FC level needed be different if one ran the generator only 1 hour per day? 4 hours per day? 8 hours per day? 12 hours per day?

    A FC level of only 1 or 2 ppm with a saltwater pool just seems really low after living with the BBB method for the last year.

    Titanium
    24,000 gallon inground freeform pool/spa circa 1983 (113 ft perimeter, 625 sq ft) with 350 gallon attached spill-over spa
    2007 2 HP, three-phase Hayward TriStar pump which is powered by an Ikeric VS-200 variable speed drive system
    1983 Laars XE Pool/Spa Heater Type ES 400,000 BTU, 1998 Hayward Super Star-Clear C-4000 cartridge filter (400 sq ft, 4 separate cartridges)
    1998 Polaris 380 pressure-side cleaner w/ 3/4 HP booster pump
    One skimmer :( and one PoolSkim :), One Supervision Galaxy LED pool lamp, Second story solar panels
    Hayward/GoldLine AquaLogic PS4 (replaced 1983 vintage dual circuit Intermatic timer)

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    JasonLion's Avatar
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    A SWG has three advantages over manually adding bleach. First it is added slowly over many hours. Assuming the SWG is running during the sunny part of the day the peak FC level can be significantly lower while the minimum level remains the same. A bleach feeder like the liquidator would have the same advantage. The minimum level is the one that really matters.

    Second there is a super-chlorination effect that takes place inside part of the SWG cell which completely wipes out anything organic that goes through that part of the SWG cell. There has been a lively debate about the significance of super-chlorination. Since very little of the water gets the super-chlorination, some people think that it can't be that important. Unfortunatly there isn't enough collective experience with continuous bleach feed systems to measure the relative impact of the super-chlorination effect for outdoor pools. There is better, though still not conclusive, evidence that it can be significant in indoor pools.

    Third, the SWG doesn't forget to put chlorine in. It is not very difficult to miss a day every once in a long while when manually adding bleach, at which point your FC level goes much lower than your nominal minimum.

    In any case, experience has show that SWGs can run at lower FC levels than pools where bleach is added once a day. Which of the three reasons is most important is not really known.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Hi,

    I'm brand new to this site and am ordering my test kit today so don't have any readings (other than from the strips).

    I've seen the shock level described elswhere as 15 and/or 25; and that this level should be maintained til all the algae is gone.

    The question is whether it's safe to swim while the CL is at this level ?

    Thanks

    pj
    miegbert

  7. Back To Top    #7
    JasonLion's Avatar
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    As long as you have a plausible CYA level then it is safe to swim with high chlorine. The correct shock level depends on your CYA level, see this table or my Pool Calculator.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    duraleigh's Avatar
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    Hi, pj,
    Welcome to the site. Your appropriate shock level is dependent on the amount of CYA in your pool. Chemgeek has a nice chart for you to use posted in the stickies. CYA-30...shock FC-15, etc.

    A huge point to remember is that bringing your FC to 15 (or whatever) is not a one-time dose. You must constantly replenish the FC as it will be consumed very rapidly killing algae. Testing and re-adding three times daily is not too much.

    The "safe to swim" is a harder question and will ultimately be your choice. I would swim in the pool very readily but others here may advise more caution. Not that the chlorine will get you (it won't at virtually any level) but that the algae and many other organics (bacteria, etc.) are active in your pool and you could pick them up.

    My thinking is the risk is minimal. There's risk in everything we do as long as we're alive and, IMHO, this does not add much to it.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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