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Thread: Calcium Hardness question

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    Calcium Hardness question

    As a long time frustrated pool owner I've stumbled onto your site and I've learned more in the last few weeks than I have in years prior, so thanks for the great info! One question I had is regarding calcium hardness. My initial test reading was 100 but I see that between 250-350 is recommended for a plaster pool. I went to a local pool store and purchased some "Hardness Plus" to add. The store employee recommended that I bump it up to the lower range, around 200, because the calcium does not go away over time and as I add water to the pool due to evaporation, that additional water(which includes calcium) will increase the CH level in the pool. So, I bought a smaller amount than I had planned to, added it to the pool and I'm now at 200. Does additional water that I add to the pool really contain that much calcium, or is the amount so small that I could bump it up now to 300 and not have to worry about it for a long time?
    13,500 gallon 26' x 15' rectangle, 6' deep in center, plaster
    Wet Institute M330 Modufilter (3 cartridge) System, 1.5 hp pump
    Kreepy Krauler, No SWG
    Taylor K-2006 Test Kit
    Central California - Extreme heat in summer, very cold in winter.

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    Mod Squad jblizzle's Avatar
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    Re: Calcium Hardness question

    Welcome to TFP!!!

    The answer greatly depends on your fill water. What is the CH of it?

    It is true that the fill water will add calcium that stays in the pool when the water evaporates. If you have very hard water and high evaporation, it can happen is a fairly short period of time (a season or so).

    That said, some members are maintaining CH levels of over 1000 by controlling the pH and TA to avoid scaling issues.

    Post up a full set of test results and we can see where you are at on everything and maybe make recommendations.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Calcium Hardness question

    Thanks for the quick response! I tested the water that comes out of my hose, got a CH reading of 40ppm. My pool gets full sun for most of the day so I usually have to add about an inch every few three or four days due to evaporation. Here's my current readings:

    FC 2 I know with my CYA I need to bump it way up.
    CC 0
    PH 7.8
    TA 90
    CH 210
    CYA 85-90

    Do you think I need to add more Calcium or stay at this level for awhile?
    13,500 gallon 26' x 15' rectangle, 6' deep in center, plaster
    Wet Institute M330 Modufilter (3 cartridge) System, 1.5 hp pump
    Kreepy Krauler, No SWG
    Taylor K-2006 Test Kit
    Central California - Extreme heat in summer, very cold in winter.

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    Richard320's Avatar
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    San Dimas, CA (LA County)
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    Re: Calcium Hardness question

    Wow, what soft water!

    The pool guy is right, it will go up, but not as fast as mine does. Probably because of my long-term battles with high CH and scaling issues, I'm biased against Calcium, but I wouldn't add any more.
    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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    Mod Squad jblizzle's Avatar
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    Re: Calcium Hardness question

    First concern is obviously the FC being WAY too low for that CYA level ... you should never let it drop below 7ppm.

    Ideally you would replace 50% of your water to get the CYA in the recommended range ... this would also make maintenance easier (and your minimum FC more in the 4-5ppm range).

    I do not really see any reason to add more CH. Even if you lower your pH some (should not let it over 7.8 or below 7.2), your water should be fine for your plaster.

    Your fill water is not going to raise the CH very faster either.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Join Date
    Jul 2012
    Location
    Bakersfield, CA
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    Re: Calcium Hardness question

    Great info guys, thanks so much! This site is awesome.
    13,500 gallon 26' x 15' rectangle, 6' deep in center, plaster
    Wet Institute M330 Modufilter (3 cartridge) System, 1.5 hp pump
    Kreepy Krauler, No SWG
    Taylor K-2006 Test Kit
    Central California - Extreme heat in summer, very cold in winter.

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