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Thread: calcium hardness, add CaCl2? pH adjust now or wait?

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    delirium330's Avatar
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    Question calcium hardness, add CaCl2? pH adjust now or wait?

    Hi All, new pool owner here, have been learning a lot and I think I've got my chemistry pretty dialed in, but have a couple of detailed questions. See below results from my latest test (I'm using the TF-100).

    1. Should I raise the calcium to 300? Or should I wait for it to potentially dip below 250? My assumption was that I'd like to avoid leaching calcium from the pool walls. My tap water replacement is very soft at 50 and my last 2 months of CH have been right between 275 and 250 with little change, but expect with more replacement water coming in with summer evaporation it will start to lower the CH further.

    2. My tap water pH is off the scales high, i.e. measures above 8.2 and is a deep red/purple when testing. My last month of test results for the pool were right at 7.5, but I just saw it creep to 7.8 in my latest test this morning. Should I add acid to bring it down to 7.5 or let it ride at 7.8 until it starts to get higher? With summer rolling around I imagine evaporation will increase which means my higher pH replacement tap water becoming more present in the pool.

    FC = 5
    pH = 7.8
    TA = 80
    CH = 250
    CYA = 45
    CC = .5 (has been 0 that past two months and saw this just slip to .5 this morning)

    Thanks!
    Built 2003, 14k Gallons, IG Pebbletec, Primary Pump: Sta-Rite Intellipro VS, Sta-Rite Series 3 S8M150 Cartridge Filter, Fiberstars Jazz Light w/Color Wheel, Polaris 280 Vacuum (Runs Zodiac PB4-60 Booster Pump) and 2 Waterfalls (Run on separate, dedicated 1HP Sta-Rite Max-E-Glas II Pump).

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    Mod Squad jblizzle's Avatar
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    Re: calcium hardness, add CaCl2? pH adjust now or wait?

    CH does not typically go down. As water evaporated, it leaves the calcium and then when you refill you add more calcium. So it is going to generally rise. You could just leave the CH as is and keep the pH in the upper 7s and be fine.

    Look at the CSI toward the bottom of PoolMath ... if you keep that in range, then the CH being a little low (with the expectation of it rising) should be safe.
    Guessing that your pool water is about 70 degrees, the numbers you posted have a CSI of right at 0 which is good. Keep the pH > 7.5 and you should be fine.
    Jason, TFP Moderator
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    Smykowski's Avatar
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    Re: calcium hardness, add CaCl2? pH adjust now or wait?

    Dialed in is right!! The fact that you're asking the questions above shows you really understand what's going on.

    I just put all of results in PoolMath, and I see no reason to touch anything (except watching FC, of course!). For CC, .5 or less is equal to 0 for our intents.

    If it's my pool, I leave it alone. Watch you pH and see how fast it moves, but your sweet spot might be in the 7.7 to 7.8 range.
    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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    delirium330's Avatar
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    Re: calcium hardness, add CaCl2? pH adjust now or wait?

    Thanks for the quick and valuable input, the calcium staying in the pool upon evaporation makes sense... duh! So even if the replacement is coming in with low calcium it should rise steadily. I was a bit overwhelmed in the beginning and just starting to use PoolMath so I never noticed the CSI portion of PoolMath so thanks for pointing that out, I should be able to make good use of that going forward. Thx again.
    Built 2003, 14k Gallons, IG Pebbletec, Primary Pump: Sta-Rite Intellipro VS, Sta-Rite Series 3 S8M150 Cartridge Filter, Fiberstars Jazz Light w/Color Wheel, Polaris 280 Vacuum (Runs Zodiac PB4-60 Booster Pump) and 2 Waterfalls (Run on separate, dedicated 1HP Sta-Rite Max-E-Glas II Pump).

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    Patrick_B's Avatar
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    Re: calcium hardness, add CaCl2? pH adjust now or wait?

    I wouldn't worry about that at all. You are doing well, so just let that CH come up on it's own. Good job!!
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