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Thread: Calcium Hardness

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    Join Date
    Oct 2011
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    Orlando, FL
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    Calcium Hardness

    How is it possible that my calcium hardness is 450 but my fill water is around 160, plus it has rained so much that I didn't even have to fill from the hose in about 2 months? I don't really understand that. Furthermore, I don't know if I should drain some water to get this down?
    screened-in 10,500 gal IG gunite pool, DiamondBrite, 1.5 HP Hayward Super II Pump, Hayward Star-Clear Plus C1200 Cartridge Filter, Hayward Pool Vac Ultra, 6 solar panel heater.

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    UnderWaterVanya's Avatar
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    Jun 2012
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    Mint Hill, NC
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    Re: Calcium Hardness

    Quote Originally Posted by versstef1
    How is it possible that my calcium hardness is 450 but my fill water is around 160, plus it has rained so much that I didn't even have to fill from the hose in about 2 months? I don't really understand that. Furthermore, I don't know if I should drain some water to get this down?
    What do you chlorinate with? Do you follow BBB methods here or something else?
    If you have any chlorine sources that are based on Calcium Hypochlorite you're adding CH with each dose.
    Was the pool maintained before by someone else? Could these levels have built up by evaporation and refills in past years?
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    37,879

    Re: Calcium Hardness

    Unless you filled the pool recently, that is not at all surprising. Calcium builds up in the pool over time when your fill water CH level is that high. Any water that evaporates it leaves all the CH behind in the pool. Then when you add more water the total amount of CH in the water increases. How quickly that happens depends on how much evaporation you are getting that is replaced with your water. Even if it is happening fairly slowly, the CH level can get quite high over time.

    CH levels around 450 are manageable. Just make sure your TA levels are reasonable (90 or lower) and that PH never gets out of control high. If CH continues to go up you may need to replace water eventually, but there is no rush to do so.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  4. Back To Top    #4

    Join Date
    Oct 2011
    Location
    Orlando, FL
    Posts
    63

    Re: Calcium Hardness

    The pool is 11 years old. I just switched from using Tri-Chlor to using liquid. From what I know, the previous owners used Tri-Chlor, as well, but I do not know if they ever had a pool service before that that might have used Cal-Hypo. In fact, they "taughtt" me how to do the pool when we moved in April 2012.

    One more clue is that I run the solar heater especially during cooler months, and I have noticed immense evaporation and no rain for months earlier in the year. So the evaporation/refill theory makes sense.

    So CH 160 fill is considered high, I suppose? So drain/refill would not be very effective? Except 160 is still way better than 450, of course. But, other than hoping for mostly rain and never having to use the hose, is there anything else I can do to keep CH from rising in the longer run?
    screened-in 10,500 gal IG gunite pool, DiamondBrite, 1.5 HP Hayward Super II Pump, Hayward Star-Clear Plus C1200 Cartridge Filter, Hayward Pool Vac Ultra, 6 solar panel heater.

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