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Thread: calcium hypochlorite and calcium hardness

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    calcium hypochlorite and calcium hardness

    Hello,
    For the last year I've been using unstabilized calcium hypochlorite to sanitize my pool. Initially I was using liquid chlorine, but switched to calcium hypochloride granules for convenience. However, after using this for a year or so I've noticed that my calcium hardness is at around 1000ppm. I understand that it's difficult to reduce this number without draining some water from the pool, but I'm curious as to whether anyone has had success using any other method. After googling and reading these forums I've heard of people reducing their calcium hardness with various degrees of success, but I'm seeing mixed information about the side effects of using water softeners and whatnot.

    Additionally, would you guys recommend that I stop using calcium hypochloride? I have been considering switching back to liquid chlorine, but it's less convient due to the limited shelf life and higher cost.

    I appreciate any advice that anyone has, thanks in advance!
    10700 gallon, in ground plaster pool.
    Cartridge filter.

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    duraleigh's Avatar
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    Re: calcium hypochlorite and calcium hardness

    but I'm curious as to whether anyone has had success using any other method.
    Not really. Draining is about the only available option. (unless you live in So Cal....tell us your city and state).

    CH of 1000 is quite high and requires very careful control of pH and TA to prevent scaling. I would bite the bullet and drain half or more of your pool. 250 - 400 ppm is what we typically suggest.

    If you continue to use Cal Hypo, the problem will only increase, despite it's convenience.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    linen's Avatar
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    Re: calcium hypochlorite and calcium hardness

    duraleigh beat me, but here is my 2 cents...
    Quote Originally Posted by supermoof
    After googling and reading these forums I've heard of people reducing their calcium hardness with various degrees of success, but I'm seeing mixed information about the side effects of using water softeners and whatnot.
    Draining and refiling is really the only proven way to reduce it. You may have read on here that some people in areas with high evaporation rates combined with high CH fill water instead use rain water to slowly reduce there CH levels by replacing pool water with rain water (pump out water before the storm then replace with rain water collected from a roof). What is your fill water CH?

    Quote Originally Posted by supermoof
    Additionally, would you guys recommend that I stop using calcium hypochloride? I have been considering switching back to liquid chlorine, but it's less convient due to the limited shelf life and higher cost.
    Yes, you are only asking for problems using that much having that high a CH level due to the use of the calhypo. Liquid chlorine/bleach is a better solution, it only adds salt, which is absolutely not a problem for a pool. Most people buy enough LC/bleach to last a few weeks so that it does not loose much before use. Another option for you could be a saltwater chlorine generator (SWG).
    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: calcium hypochlorite and calcium hardness

    Great, thanks for the advice. I'll look into having it drained and switching back to liquid chlorine. I'm in Austin TX, I believe the water here is relatively hard already.
    10700 gallon, in ground plaster pool.
    Cartridge filter.

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    linen's Avatar
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    Re: calcium hypochlorite and calcium hardness

    Just keep in mind that when you drain it, if your ground water level is high, then you risk floating your pool. Do you know if you have high ground water?
    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: calcium hypochlorite and calcium hardness

    I'm not sure what the ground water level is, but based on the area it's probably relatively high. I'm not confident enough to do this myself so I'll find a reputable pool company anyway. When ground water level is high, how do you prevent the pool from floating?
    10700 gallon, in ground plaster pool.
    Cartridge filter.

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    linen's Avatar
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    Re: calcium hypochlorite and calcium hardness

    Generally, partial drains and refills are used then though this ends up using more water. Others have added slowly from one end and removed at the same rate from the other end (or from the floor drain) of the pool to reduce mixing.
    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: calcium hypochlorite and calcium hardness

    Great, thanks.
    10700 gallon, in ground plaster pool.
    Cartridge filter.

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