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Thread: Hard water calcium scale question

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    FirstVallartaPool's Avatar
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    Hard water calcium scale question

    OK as you can see in my sig we battle scale build up constantly here with our city water on everything from faucets to showerheads etc. However when I do a calcium hardness test with tf-100 I test a low 125 such that I need to add something [calcium chloride] to bring it up. I'm confused can someone shed some light on this?
    Thanks!
    Pool 3800 gaĺlon glass tiled concrete approximately 10 years old/ Puerto Vallarta
    Hayward sand filter S166t.
    Pool Pump Silver10/1115 1hp
    Heat siphon Sx3.25hp
    Hard Municipal Water tf-100 test kit

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    Mod Squad pooldv's Avatar
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    Re: Hard water calcium scale question

    CH is not the only factor for determining scale potential. Enter all your test results in PoolMath and it will give you a CSI number. Keep that number between -0.3 and 0 to avoid scale in your pool. More here, Pool School - Calcium Scaling
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    FirstVallartaPool's Avatar
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    Re: Hard water calcium scale question

    Right but I'm still only testing 150 ch for the municipal water in our house yet we still have massive scale calcium build up.. i still have yet to hear a good explanation regarding this...
    Incidentally my csi is -.13
    Pool 3800 gaĺlon glass tiled concrete approximately 10 years old/ Puerto Vallarta
    Hayward sand filter S166t.
    Pool Pump Silver10/1115 1hp
    Heat siphon Sx3.25hp
    Hard Municipal Water tf-100 test kit

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    Texas Splash's Avatar
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    Re: Hard water calcium scale question

    Also remember that even if your fill water is only 150, CH never leaves the pool unless you exchange that water. So basically the CH in the pool keeps building higher & higher with new refills following evaporation. Your CH may be 200 in May, then grow to 250 or more by June or July depending upon how much more water was added. The only way CH itself will drop is if you drain water and replace it with "soft" water. So to compensate for the CH growing, we make sure to never let pH and/or TA get too high to keep the CSI balanced.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    FirstVallartaPool's Avatar
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    Re: Hard water calcium scale question

    OK thanks that's good to know so with my csi at -.13 I will leave it as it will increase over time. But i still dont understand how we battle calcium scale build up in the house on faucets etc when our water is only ch 150?

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    Mod Squad pooldv's Avatar
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    Re: Hard water calcium scale question

    Because CH is not the only factor in determining scale potential. It is a combination of alkalinity, pH and CH. In the right combination CH at 150 can also leave scale. Just like it is possible for pools with CH at 1200 not to have scale with the right pH and TA. It is all about the scale potential of all of the measurements.

    Test your tap water and figure out what the CSI is.
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    FirstVallartaPool's Avatar
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    Re: Hard water calcium scale question

    Ah OK I get it. I just assumed due to all scale build up on faucets tap water would test high on a ch test. This forum is teaching plenty. Thanks!
    Pool 3800 gaĺlon glass tiled concrete approximately 10 years old/ Puerto Vallarta
    Hayward sand filter S166t.
    Pool Pump Silver10/1115 1hp
    Heat siphon Sx3.25hp
    Hard Municipal Water tf-100 test kit

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