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Thread: Calcium Hardness

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    Calcium Hardness

    CH has increased over time to 415. At what point do i need to drain a little and add new fill? Water is very expensive where i live. I'm guessing the calcium came from the city water since i only use liq chlorine, acid, backing soda.

    from pool school; A plaster pool should have CH levels between 250 and 350 if possible. You lower calcium by replacing water or using a reverse osmosis water treatment.

    FC4
    TC4
    CC0
    PH 7.8
    TA 80
    CYA 40
    18k, IG, chlorine, plaster, sand, 12yrs, new plaster 2013, Texas

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    Re: Calcium Hardness

    A Calcium hardness of 415 is quite manageable. Once you go outside of the recommended range, it can be helpful to use the pool calculator to calculate your CSI. To calculate CSI you need to enter pH, TA, CH, CYA, Temp, Borate, and Salt.

    Maintain a CSI of less than +0.3 and you should be fine.

    http://www.poolcalculator.com/

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    Smykowski's Avatar
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    Re: Calcium Hardness

    What's your pool's temp right now? Depending on temp you're in the .25-.35 range. If needed, you can drop your pH by a point or two and you'll be fine.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
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    Patrick_B's Avatar
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    Re: Calcium Hardness

    Also, the availability of RO pool treatment is exceedingly rare. Phoenix and somewhere in CA seem to be the only places it exists.

    James and smykowski are right, and there are many thousands with no choice like me. I run >700 in my vinyl pool and have for years. When I build, I am trucking in the first fill for a much better 350-450 and it will be the best I can hope for here. It's very do-able
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    Re: Calcium Hardness

    As already mentioned, your CH level isn't so high that you have to take action to fix it during this swimming season. Do you close your pool in your part of Texas? If ya do, drain it down some at closing and let the winter & spring rains provide you free calcium-free, CYA-free water. You could even divert one or more of your rain gutter downspouts to the pool to collect more water.

    At the beginning of next swimming season, check your CH & CYA levels and drain/refill a bit more, if necessary.

    Good luck!
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    Re: Calcium Hardness

    current temp 86, keep pool open all year. RO would be nice but it might be higher than partial drain and refill. When draining, how much do u drain, 50%? Drain by backwashing cause i would have to rent a suction pump.

    thanks
    18k, IG, chlorine, plaster, sand, 12yrs, new plaster 2013, Texas

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    Smykowski's Avatar
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    Re: Calcium Hardness

    Based on all of those numbers, your current CSI is +0.38

    If you drop your pH to 7.6, your CSI goes to 0.19
    If you drop your pH to 7.5, your CSI goes to 0.09

    There's no reason to drain and refill your pool yet. Just keep your pH a touch lower and you're fine.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
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    Patrick_B's Avatar
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    Re: Calcium Hardness

    Quote Originally Posted by Derosa
    current temp 86, keep pool open all year. RO would be nice but it might be higher than partial drain and refill. When draining, how much do u drain, 50%? Drain by backwashing cause i would have to rent a suction pump.

    thanks
    I don't know where you are in TX, but you won't likely find RO treatment. Even so, what you have isn't that bad. Perhaps even more importantly, what is your fill water CH?
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    Re: Calcium Hardness

    austin, texas
    fill; Austin tap water is considered moderately hard. Hardness testing conducted throughout 2011 showed we have an average hardness of 98 milligrams per liter or about 5.7 grains per gallons.
    18k, IG, chlorine, plaster, sand, 12yrs, new plaster 2013, Texas

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    Patrick_B's Avatar
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    Re: Calcium Hardness

    Good deal then. Over time your pool CH will come down with that as long as you stay away from Cal-Hypo
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    Re: Calcium Hardness

    Yours is pretty easy to manage by keeping the pH and TA on the lower side of the range. Play with pool calculator a bit to see the relationship. It is possible to manage much higher CH by keeping pH and TA on the low side.

    Splash-out and backwashing will help keep CH down since you'll lose some higher-calcium water, and replace it with lower-calcium water. If your CH gets really high in spite of this, there is an RO service for the Austin area. You're nowhere near needing this, yet, though.
    Outdoor 14,000 gallon IG plaster pool built in 2000 with spillover spa, 2 hp WhisperFlo pump with MagneTek motor, Sta-Rite cartridge pool filter with 300 ft2 filtration area and 0.33 gpm/ft2 filtration rate, Aquabot Rapids 4WD robotic pool cleaner, Raypak digital gas heater, and Intermatic mechanical timer located in the Dallas-Fort Worth metroplex

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    Richard320's Avatar
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    Re: Calcium Hardness

    415 is lower than I've ever been. Don't sweat it. Just plug your numbers into the pool calculator and let it figure out the CSI. If it shows risk of scaling, lower pH. If that's not enough, lower pH and aggressively aerate and repeat to lower TA while maintaining safe pH levels until CSI is good.

    See how much rain water you can capture - that's the best way to dilute the pool with Calcium-free water. And it's free, aside from maybe some downspout extensions.
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    Re: Calcium Hardness

    If you have 98 PPM TH as you mention, take every possible chance to replenish with that source. I only wish I had that for makeup.

    I understand limited water and restrictions, but your makeup is the key here. With what you have, 410 can be easily reduced with that. Keep it simple.
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