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Thread: low Calcium Hardness (CH) in pool with 2-month-old plaster

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    low Calcium Hardness (CH) in pool with 2-month-old plaster

    Hi everyone, a simple question about Calcium Hardness (CH). The new plaster on my pool is now a few days under 2 months old. I had the impression from reading other topics in this forum that new plaster tends to leak calcium into the pool. I measured CH:
    on 4/27: 160
    5/11: 130

    I thought maybe my chemicals were old and that could affect it, so I took a sample to a pool store, and they read 110.

    Chlorine 3.0 (SWG)
    pH 7.8
    TA 60
    CYA 40-50
    Salt: 2900

    I added 15 oz. MA (target 7.5), 61 oz. bicarb (target 80), and 1 bag of salt.

    I just bought CYA, which my SWG recommends to be 50-75, and 75-85 for temperatures above 30C (86F). Given that here in South Florida the pool can reach around 85+F, I figured I should target 75-80, especially once I add a solar heater. I'll add 67 oz volume CYA per Pool Calculator.

    (I am soon going to add Borax, in case that matters.)

    In my previous pool (10-year plaster) in this same area, I never had any CH issues, in fact (don't shoot!) I started checking it very infrequently because it never needed adjustment, so I delayed in testing in my new pool, especially since I figured the new plaster would be releasing plaster.

    I bought Tetra Express anhydrous calcium chloride 93-97% at the pool store. The pool calculator says to add 325 oz. by volume calcium chloride for a target CH of 300. Before doing so, I just wanted to run by you guys, just in case I'm missing something.

    An aside: I asked the pool service guy that handles the new plaster for the first month for my pool contractor if he'd ever heard of Borax in a pool, and he hadn't. I once asked another pool service guy the same thing, and hadn't either. Is that the norm, given that most pool guys use the old techniques they're familiar with, and many/most don't have an interest in looking at a forum like this or getting new ideas (no offense to any pool servicemen reading this - obviously you wouldn't be one of those!)? Or does that mean that these particular guys should definitely not be who I call e.g. if I get tired of taking care of the pool myself and want someone to take care of it?
    15.5 k gallon. IG. plaster. Pool/spa pump: Jandy Zodiac FloPro FHPM 2.0-2 (0.25 and 2.0 HP 2-speed). Water feature pump: Jandy Zodiac Stealth Pro Series, SHPF 3.0 (3.0 HP). Filter: 250 SF cartridge. Surface area 290 SF. Jandy AquaPure SWG and PureLink. Aqualink controls. Jandy Legacy Pool and Spa Heater by Zodiac 400,000 BTU - natural gas. Heliocol solar panels. Built 3/2013.

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    BoDarville's Avatar
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    Re: low Calcium Hardness (CH) in pool with 2-month-old plast

    haz:

    Most plaster installers have a "break-in" process that the pool owner must follow in order to maintain the warranty on the plaster. If you are still in that time period, I would follow the plasterer's instructions to a "T" - no more and no less. If you are outside that "break-in" period or they never gave any such instructions, then you can add CH per the Pool Calculator.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
    A good test kit is an investment, not an expense.

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    Re: low Calcium Hardness (CH) in pool with 2-month-old plast

    They took care of the pool, chemicals, etc. for around 1.5 months and then handed it over to me, now ~2 weeks ago. They gave me an FAQ sheet and other papers about pool maintenance, but it didn't say anything specific about calcium, and they didn't mention it. They just mentioned that the first 6 months you have to be more on top of the chemicals or something.
    15.5 k gallon. IG. plaster. Pool/spa pump: Jandy Zodiac FloPro FHPM 2.0-2 (0.25 and 2.0 HP 2-speed). Water feature pump: Jandy Zodiac Stealth Pro Series, SHPF 3.0 (3.0 HP). Filter: 250 SF cartridge. Surface area 290 SF. Jandy AquaPure SWG and PureLink. Aqualink controls. Jandy Legacy Pool and Spa Heater by Zodiac 400,000 BTU - natural gas. Heliocol solar panels. Built 3/2013.

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    BoDarville's Avatar
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    Re: low Calcium Hardness (CH) in pool with 2-month-old plast

    Then I would say you are good to go in adding your calcium.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
    A good test kit is an investment, not an expense.

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    Re: low Calcium Hardness (CH) in pool with 2-month-old plast

    Yeah, add enough calcium to get to 250-300. Once the plaster cures completely (which can take months) the CH will stabilize and there is no need to check it but maybe 2-3 times each summer.

    You will find VERY few pool guys who understand pool water chemistry as in depth as the members on this forum. If you turn your pool management over to a service, the onus will be on you to insist they do it the way you have learned here and you will likely get some resistance.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: low Calcium Hardness (CH) in pool with 2-month-old plast

    Thanks guys - will add the calcium. I ended up buying a 50-lb bag as it was more economical that 3 8-lb bags - any good rec's for storing the extra? I know it has to be air-tight to avoid moisture, so I was going to put what's left in the biggest ziplock bags I have.

    duraleigh - yes, that's always been my fear w/ the pool service, making sure they do the right thing. With an SWG, there's less damage they can do, but still.
    15.5 k gallon. IG. plaster. Pool/spa pump: Jandy Zodiac FloPro FHPM 2.0-2 (0.25 and 2.0 HP 2-speed). Water feature pump: Jandy Zodiac Stealth Pro Series, SHPF 3.0 (3.0 HP). Filter: 250 SF cartridge. Surface area 290 SF. Jandy AquaPure SWG and PureLink. Aqualink controls. Jandy Legacy Pool and Spa Heater by Zodiac 400,000 BTU - natural gas. Heliocol solar panels. Built 3/2013.

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