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Thread: Chlorine Levels

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    Chlorine Levels

    I cant maintain chlorine levels in my tub, no matter how much chlorine I add the free chlorine level doesn't seem to change. Tested my test strips in a glass of hot tub water and added some chlorine granules and strip showed the chlorine in there with no problem. Have now added loads of chlorine but no change, free chlorine still showing as zero!

    Tub recently restarted after several weeks, dosed with non chlorine shock and chlorine, ph and alkilinity levels showing as ok

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    Mod Squad Bama Rambler's Avatar
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    Re: Chlorine Levels

    Welcome to TFP.

    Did you drain and refill the tub? Did you decontaminate it when you restarted it?

    Telling us you added loads of chlorine doesn't really tell us anything. How much and what type have you used?
    Dave J. TFP Moderator
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    Re: Chlorine Levels

    Quote Originally Posted by Bama Rambler
    Welcome to TFP.

    Did you drain and refill the tub? Did you decontaminate it when you restarted it?

    Telling us you added loads of chlorine doesn't really tell us anything. How much and what type have you used?

    I have added around 100g of FiClor chlorine granules and 40g of Fi Clor non chlorine shock, tub is approx 1000litres. I didn't drain and refill.

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    Mod Squad Bama Rambler's Avatar
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    Re: Chlorine Levels

    Chem Geek is our resident spa expert, maybe he'll chime in.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Chlorine Levels

    what exactly do you mean restarted after several weeks?

    If its been sitting for several weeks either empty with water in the pipes, or full of water and not treated/circulated even a little bit...sounds like you definatly have to decontaminate. I recently read it does not take very long for biofilms to start in the pipe when not chlorinated.
    12500 gallons, 24 foot round above ground
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    linen's Avatar
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    Re: Chlorine Levels

    Do you have a drop based OTO Total Chlorine test...it is usually attached to same block as a ph test...looks something like the the thing in the middle of this with the yellow and red caps:

    If you do, test with that and post what you get.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Chlorine Levels

    I think a decontamination is in order (SeaKlear Spa System Flush) and you should get a proper test kit (TFTestkits TF-100 or Taylor K-2006). See Using Chlorine in a Spa, but after you decontaminate I would target a TA of 50 ppm and definitely use 50 ppm Borates.
    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: Chlorine Levels

    Thanks Chemgeek, sorry to be thick but I dont understand the second part of your message:

    I would target a TA of 50 ppm and definitely use 50 ppm Borates.

    Also where can I acquire the stuff?

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    Re: Chlorine Levels

    Be sure to get the proper test kit. Then do the decontamination procedure. After all that, you can move to balancing your fresh fill water. Your Total Alkalinity (TA) will probably be higher than 50 ppm from your fill water so to lower it you follow the procedure in Lower Total Alkalinity. For the 50 ppm Borates, the easiest method is to add boric acid which you can get as described in the Borate section at the bottom of Recommended Pool Chemicals.
    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: Chlorine Levels

    Think I've diagnosed the problem! After adding another 40g of chlorine granules and seeing no change in FC level, I've added 40ml of bleach and bingo, now got a healthy chlorine level! I suspect my chlorine granules are goosed, they are from last year and are clumped together from moisture so suspect they've reacted with the moisture and lost most of the chlorine, I'll monitor chemistry for a couple of days before using! Chlorine TABLETs on order!

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    Re: Chlorine Levels

    I'm glad you figured out what was going on. That's a lot easier to handle that having to go through the full decontamination with a water change. Usually solid chlorine doesn't go bad that quickly, but it sounds like it got moisture in it and in that case it will break down.
    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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