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Thread: What's eating my chlorine?

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    What's eating my chlorine?

    I've noticed recently that more and more chlorine was needed to maintain FC. The water has been crystal clear since I filled it about a month ago. Chemistry has been right on other than allowing FC to drop below the minimum a couple of times. CC has never registered more than .5, and that's only been in the last several days.

    So yesterday I decided to SLAM in order to get ahead of whatever might be in there. I accidentally brought FC to 25 (forgot to change values in poolmath). Anyway, last night it was 25, this morning it was 20, and now it's 15. Is this normal for water that's always been clear and never shown visible signs of algae?

    FC 15
    CC 0.5
    TA 150
    CH 275
    PH 7.6 (before slam)
    CYA 40
    26K IG painted gunite / 24" Cristal-flo (prefilter) to Pentair Warrior DE filter / 1hp Hayward Super II / TF-100

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    JoyfulNoise's Avatar
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    Re: What's eating my chlorine?

    Quote Originally Posted by johnly View Post
    I've noticed recently that more and more chlorine was needed to maintain FC. The water has been crystal clear since I filled it about a month ago. Chemistry has been right on other than allowing FC to drop below the minimum a couple of times. CC has never registered more than .5, and that's only been in the last several days.

    So yesterday I decided to SLAM in order to get ahead of whatever might be in there. I accidentally brought FC to 25 (forgot to change values in poolmath). Anyway, last night it was 25, this morning it was 20, and now it's 15. Is this normal for water that's always been clear and never shown visible signs of algae?

    FC 15
    CC 5.5
    TA 150
    CH 275
    PH 7.6 (before slam)
    CYA 40
    I'd repeat the OCLT again but if your FC loss is that high, you've got something in your water. Remember, here at TFP we have a saying -

    CLEAR water is NOT a sign of CLEAN water!

    or, to put is more succinctly,

    Clear does not equal clean!

    You likely need to SLAM.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    ned8377's Avatar
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    Re: What's eating my chlorine?

    There are two things that lower chlorine, sunlight and algae/bacteria. If it dropped 5 ppm over night you have something.
    True L 45,000 gal Hayward IG vinyl pool. Hayward Tristar 2.40 THP; 1.5 FRHP/1.60 SF. Hayward Model # S310T2 Sand Filter. Aqua Rite T-15. Aqua Comfort 154,000 BTU Heat Pump. TF-100

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    Mod Squad pooldv's Avatar
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    Re: What's eating my chlorine?

    Yep, I had to SLAM last summer with crystal clear water and no CC. I had some algae growing in patches in the rocks/grout under the waterfall, some in the pool cleaner and some junk behind the light. I was also lazy about brushing last summer. Now I try to brush every week or two for sure.
    TFP Moderator
    If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: What's eating my chlorine?

    Thanks for the replies. Yeah, this is one lesson I will learn only once. I just dislike brushing. Do suction side cleaners eliminate the need for brushing? If not, that's fine. I also dislike folding laundry, but I do it anyway.
    26K IG painted gunite / 24" Cristal-flo (prefilter) to Pentair Warrior DE filter / 1hp Hayward Super II / TF-100

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    Re: What's eating my chlorine?

    Quote Originally Posted by johnly View Post
    I've noticed recently that more and more chlorine was needed to maintain FC. The water has been crystal clear since I filled it about a month ago. Chemistry has been right on other than allowing FC to drop below the minimum a couple of times. CC has never registered more than .5, and that's only been in the last several days.

    So yesterday I decided to SLAM in order to get ahead of whatever might be in there. I accidentally brought FC to 25 (forgot to change values in poolmath). Anyway, last night it was 25, this morning it was 20, and now it's 15. Is this normal for water that's always been clear and never shown visible signs of algae?

    FC 15
    CC 5.5
    TA 150
    CH 275
    PH 7.6 (before slam)
    CYA 40
    Have you been using non-chlorine shock (MPS)?

    That CC 5.5ppm is showing that your chlorine is working hard to oxidize something .....

    Dom
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

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    Re: What's eating my chlorine?

    Oops, that CC should have been 0.5. And no, I've not used any pool "products" - following TFP to the letter. Very grateful to this site and it's contributors.

    This morning's FC is 16, same as it was last night. I win!
    26K IG painted gunite / 24" Cristal-flo (prefilter) to Pentair Warrior DE filter / 1hp Hayward Super II / TF-100

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    Mod Squad pooldv's Avatar
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    Re: What's eating my chlorine?

    Nice! Good answer!
    TFP Moderator
    If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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