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Thread: Using trichlor tabs to bring up CYA?

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    Using trichlor tabs to bring up CYA?

    Hi all,

    I've managed to SLAM my pool into a good state after opening earlier this month, but my CYA is still kind of low. (It's ~20ppm for my 18700 gal). I'm low on pure CYA, but I have a bunch of 3" trichlor tabs that I figured I could use to bring it up.

    The tablets say they are 93.6% trichlor, 2.5% zinc sulfate monohydrate, and 3.9% "other", which is where I guess the CYA is hiding.

    I added two 3" hockey pucks to my floating tablet holders. Any idea what kind of increase is to be expected for FC and CYA? FC pre addition was 2ppm and CYA was ~20ppm.

    Thanks,
    ~20k gal inground vinyl lined pool
    Hayward Perflex DE filter
    Aqua bot cleaner

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    JasonLion's Avatar
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    Re: Using trichlor tabs to bring up CYA?

    Take a look at the effects of adding chemicals section at the bottom of Pool Calculator to see how they will affect the water, and watch out because they lower PH.

    Trichlor adds CYA fairly slowly, but will eventually get there.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Richard320's Avatar
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    Re: Using trichlor tabs to bring up CYA?

    The CYA is actually within the 93.6% 1,3,5-Trichloro-1,3,5-triazinane-2,4,6-trione component.
    The zinc stuff is an algaecide. Too much of the zinc in the water can cause metal stains
    The "other" is probably clay used as a binder

    Trichlor is very acidic. If your pH or TA are towards the low end, you could drive pH too low.

    Plug all your values into poolmath and then scroll down to where it says Effects of Adding Chemicals and see what each 7 oz puck will do to your chemistry.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Using trichlor tabs to bring up CYA?

    Ah, I didn't know about that drop-down at the bottom. Assuming a 3" puck weighs 8 oz (which someone claimed online), 2 pucks would raise my FC by 5.9 and CYA by 3.6 .... meaning I need to use about 11 of those pucks to raise my CYA all the way.

    Do trichlor pucks go bad? Mine have been sitting in the garage from the previous owners for at least a year.

    Also, any guidelines for CYA target in the northeast? (I'm in Hudson Valley NY)... Sounds like people down south with lots of sun keep the CYA pretty high but not sure what to target mine. I picked 40 but that was arbitrary. Basically minimizing chlorine usage while also minimizing daily loss as much as possible.
    ~20k gal inground vinyl lined pool
    Hayward Perflex DE filter
    Aqua bot cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Using trichlor tabs to bring up CYA?

    If they stay dry, they do not go bad. I needed to add CYA this year and the 4 pounds I bought was not quite enough, so I too used some tablets to get the last bit.
    Jason, TFP Moderator
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    Re: Using trichlor tabs to bring up CYA?

    Also, any guidelines for CYA target in the northeast? (I'm in Hudson Valley NY)... Sounds like people down south with lots of sun keep the CYA pretty high but not sure what to target mine. I picked 40 but that was arbitrary.
    40 is what I would have suggested for your climate.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Richard320's Avatar
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    Re: Using trichlor tabs to bring up CYA?

    Quote Originally Posted by pleasantpool View Post
    Ah, I didn't know about that drop-down at the bottom. Assuming a 3" puck weighs 8 oz (which someone claimed online), 2 pucks would raise my FC by 5.9 and CYA by 3.6 .... meaning I need to use about 11 of those pucks to raise my CYA all the way.

    Do trichlor pucks go bad? Mine have been sitting in the garage from the previous owners for at least a year.

    Also, any guidelines for CYA target in the northeast? (I'm in Hudson Valley NY)... Sounds like people down south with lots of sun keep the CYA pretty high but not sure what to target mine. I picked 40 but that was arbitrary. Basically minimizing chlorine usage while also minimizing daily loss as much as possible.
    Pucks are either 7 or 8 oz, generally. Weigh one on a diet scale or a postage scale and see what you have. I went with 7 oz, since they're only 93% pure.

    Did you also note the pH drop each puck causes?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Using trichlor tabs to bring up CYA?

    The excess Leslies 3" Trichloro pucks I have weigh in at 8 ozs each.
    Having just done a mini pebble replaster, I'm looking to use them up and be rid of them.

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    dattia's Avatar
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    Re: Using trichlor tabs to bring up CYA?

    I used some pucks during my slam last week, as I had no CYA at the time and my pH dropped to 6.8 (I had no idea why until now ). Just keep that in mind.
    27' round AG
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