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Thread: calcium hardness

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    calcium hardness

    I live in IN and would like to maintain my calcium harness at 350 during the summer.In our heat, I have to add 500 gals water/week due to evaporation. Our water has 60-120 ppm of Calcium hardness (on the soft side). I am currently in the process of draining about 60% of water from our 25,000 gallon inground pool as my Cya was at 80.I'd like to maintain a Ca Hardness level of 350ppm once I get the CYA problem corrected. Over the next 3 hot months will my Ca hardness get high enough to cause scaling problems if I manage to keep my pH at 7.4-7.6?
    Thanks, CAK57

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    Re: metal sequestrant

    I am doing a drain of about 60% of my water & anticipate zero chlorine after. Should I add a metal sequestrant before I add chlorine? If so, what brand would you recommend?
    Thanks, CAK57

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    calcium hardness

    Another thing you will want to do is make sure you add borates (Borax).

    This will give you additional pH buffering, and will allow you to further reduce your TA.

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    Re: Pool opening

    I have read that calcium harness should be established first before adjusting any other water parameters upon pool opening. True? (even before shocking?)
    Thanks, CAK57

  5. Back To Top    #5

    Re: Algacide usage

    Per TFP pool opening guidelines, I see that high quality algacide is recommended after all othe water parameters balanced. What brand do you recommend? Also, do you recommended adding an algacide weekly?

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    Re: metal sequestrants weekly/biweekly

    I have water with no copper or iron in it and yet the pool store says to add a weekly sequestrant. Should I?
    Thanks, CAK57

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    Re: calcium hardness

    Didn't notice that this was from the same person before the threads merged.... Nevermind.

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    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: calcium hardness

    I've moved and merged all your posts. Lets keep everything here.

    There are other things a lot more important than CH that should be adjusted first. Post a full set of test results and how you got them.

    Algaecide is an un-necessary expense unless you have some compelling reason to need it. Weekly algaecide is a waste of money.

    If you don't have metals in your water then sequestrant is a waste of money also.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    dmanb2b's Avatar
    Join Date
    Apr 2009

    Re: calcium hardness

    Not to pile on, but depending on the pool surface you have, raising calcium hardness may not be necessary either. CYA of 80 can be dealt with. I there a strong preference to reduce CYA? Perhaps you plan to use trichlor for chlorination?

    PH should always be balanced first, then FC and CYA.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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  10. Back To Top    #10

    calcium hardness

    Do you recommend using clarifiers weekly as the pool stores do?
    Thanks, CAK57

  11. Back To Top    #11

    Re: calcium hardness

    Thanks much in answer to all my questions. I'm still wondering what an appropriate level of calcium level I should establish after I refill my pool. Our local water source is 50-54ppm as it leaves the plant. 350 ppm was my goal, but with summer evaporation at 500gal/week, I wonder if I should start lower, lie 300 ppm.
    I am so new to the computer & TFP that I'm not sure how to post my test numbers (i.e. what link to go to). Appreciate guidance.

  12. Back To Top    #12

    Join Date
    Jun 2007

    Re: calcium hardness

    Quote Originally Posted by cak57
    Do you recommend using clarifiers weekly as the pool stores do?
    With properly balanced water (FC, CC, CYA, PH, TA, CH, filtering, brushing weekly, etc.) There are seldom reasons to add clarifiers OR algaecide, especially weekly!

    Most of us use chlorine (good old 6% bleach or liquid chlorine if it's available), acid for dropping PH, CYA for stabilizing the chlorine against loss from the sun, baking soda, salt (water-softener salt) to make the water feel better on the skin, etc.

    If there is a metal problem then a metal sequestrant (sp?), but we prefer to NOT put anything extra into the water that we don't have to.

    It sounds like you *might* be getting "pool-stored"...

    1. What are you using to measure FC, CYA, etc.? We recommend that measure your own chemical levels. It's more accurate than a pool store, and it takes about 5 minutes a day.

    2. What are you using to chlorinate the pool?

    I'd STRONGLY recommend that you take the time to read through the articles in "Pool School". It's an education that is worth your time, much more so than pool store chemicals!

    Just post the chemical levels in your response:

    Terry in NC
    Triad Region of NC
    18x37 Vinyl IG (24,000 gal.), BBB & GoldLine AquaLogic PS4 SWG, Hayward 1 HP Superpump / Hayward Sand Filter / Polaris 280 cleaner / 6 deck jets / Sheer Descent Waterfall (in coping) / Brick Red Concrete Coping / Stamped Concrete Deck
    Lots of oak trees, maple trees, *and* leaves!

  13. Back To Top    #13
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: calcium hardness

    Is the pool surface plaster, fiberglass, or vinyl? You may not need that much Calcium.

    Just doing some quick math, here. If the water is currently at 350 and the fill water is 120, when you're done, you should be near 212 already. Why go any higher?

    500 gallons is 2% of your pool water. So every week you'd be adding .02x120 = 2.4 ppm CH/week. It will take a long time to build up that way...

    Why drain 60% anyway? 80 CYA is do-able; 60 is not unreasonable if you get a lot of direct sunlight. The actual chlorine demand will stay about the same at a higher CYA level; all you need to do is maintain a higher minimum. Of course, a lower CYA makes it easier to bring the pool up to shock level in case you get careless. But if you're the diligent type, you won't get an algae bloom.

    Just some things to think about.
    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.
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  14. Back To Top    #14

    Re: calcium hardness

    Thanks so much again to everyone who commented. After draining my 25,000gal plaster pool of about 60%+ of its water, my Taylor-2006 test kit results are as follows:
    FC .3
    CC .3
    pH 7.9
    TA 190
    CYA about 20
    Ca Hardness 130 (tested by Leslie's because I discovered that my original Ca hardness reading of 350 by Taylor testing was wrong...It was 240 at Leslie's). I knew it was off because my other numbers matched with Leslie's. BTW.. I had the same discrepant Ca H result at another pool store, which only further confirmed my error. I asked why and the Leslie employee said that Calcium Hardness is extremely difficult to test without a paddle stirrer.
    She went on to say that even if you really swirled the Taylor test solution, the calcium falls out of solution so rapidly, that you end up adding too many drops and get a falsely elevated reading.
    -Wasky Dive-How much Borax to add?
    -Richard 320-I so appreciate the Ca Hardness calcs!

  15. Back To Top    #15

    Join Date
    Aug 2010
    Dallas, TX

    Re: calcium hardness

    Did you refill or are you sitting at 40% full?

    Chances are you are going to have to shock. Is your pool turning cloudy or green?

    If you shock with cal hypo, you'll bring your CH up with it.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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  16. Back To Top    #16

    Re: calcium hardness

    My pool is full. The FC and CC are at 4 after I added 7 cups liquid chlorine about 4 hours ago.
    The pool is clear and I don't want to shock as we are having swimmers tomorrow. Hope it's ok that my TA is 190. I'm thinking of waiting to alter TA until after the weekend. The Ca Hardness will have to wait in between adjusting TA I understand.

  17. Back To Top    #17

    Join Date
    Jun 2011
    Las Vegas, NV

    Re: calcium hardness

    Quote Originally Posted by cak57
    Hope it's ok that my TA is 190. I'm thinking of waiting to alter TA until after the weekend. The Ca Hardness will have to wait in between adjusting TA I understand.
    Just add some muriatic acid and it'll lower both your TA and pH (your pH is also high).
    It won't be a problem to add it a little while before swimmers come over.
    My pool is 15,000 gallons fresh water with a Hayward C5025 cartridge filter system; inground plaster. I'm still learning the details of the pool; bought the house Oct 2014.

  18. Back To Top    #18

    Re: calcium hardness

    iflyjetsss: Thanks. I forgot to mention that pH dropped to 7.5, but TA remained at 190. My chorine is fine. That's why I think it will be ok to deal w/TA after the weekend.

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