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Thread: White substance on hot tub flagstone overflow & waterline tile

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    Join Date
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    White substance on hot tub flagstone overflow & waterline tile

    Can anyone tell me what this white stuff is on the very bottom and on both sides of my hot tub flagstone overflow and on the waterline tile directly below it. This is the only place it is on the entire pool. All my numbers are are of good value. I tried rubbing it with a pumice stone before I took this pic. I wouldn't think it is scale as all my values have been spot on since my pool has been built. This is a new pool of about 3 months.
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    Nov 2014 - 25,000 IG Freeform 3.5'-7' w/ 18" Spa, 7 Ton Rock Waterfall, Bordeaux PebbleSheen, UV & Corona Discharge Ozone, HC-3315 Chlorinator, Jandy CV580 Cartridge Filter, Jandy LXI 400K Heater, Polaris 280 Cleaner, Jandy LED Pool2 & Spa1, AquaLink PDA
    Jandy JEP2.0VS (Filter), Jandy SHPM2.5 (Spa), Jandy FHPM1.5 (Waterfall), Polaris PB4-60 (Booster) - 2006C

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    JasonLion's Avatar
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    Re: White substance on hot tub flagstone overflow & waterline tile

    It is a mixture of calcium and salt that accumulates when water evaporates off of those areas. The rest of the overflow wall gets wet enough that the water doesn't ever completely evaporate. But near the edge it will get enough spray to get a little wet, but not enough to prevent evaporation from leaving behind all the solids that are in the water.

    It should come off fairly easily with a dilute muriatic acid solution.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: White substance on hot tub flagstone overflow & waterline tile

    Quote Originally Posted by JasonLion View Post
    It is a mixture of calcium and salt that accumulates when water evaporates off of those areas. The rest of the overflow wall gets wet enough that the water doesn't ever completely evaporate. But near the edge it will get enough spray to get a little wet, but not enough to prevent evaporation from leaving behind all the solids that are in the water.

    It should come off fairly easily with a dilute muriatic acid solution.
    What dilution rate should I use? I am assuming muriatic acid and water.
    Nov 2014 - 25,000 IG Freeform 3.5'-7' w/ 18" Spa, 7 Ton Rock Waterfall, Bordeaux PebbleSheen, UV & Corona Discharge Ozone, HC-3315 Chlorinator, Jandy CV580 Cartridge Filter, Jandy LXI 400K Heater, Polaris 280 Cleaner, Jandy LED Pool2 & Spa1, AquaLink PDA
    Jandy JEP2.0VS (Filter), Jandy SHPM2.5 (Spa), Jandy FHPM1.5 (Waterfall), Polaris PB4-60 (Booster) - 2006C

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    JasonLion's Avatar
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    Re: White substance on hot tub flagstone overflow & waterline tile

    Yes, muriatic and water. Add one part of acid to ten parts of water (assuming 31.45% acid). When you have done this a few times, you can use higher concentrations, but they are a little more difficult to work with and you only have a small area to work on.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: White substance on hot tub flagstone overflow & waterline tile

    Quote Originally Posted by JasonLion View Post
    Yes, muriatic and water. Add one part of acid to ten parts of water (assuming 31.45% acid). When you have done this a few times, you can use higher concentrations, but they are a little more difficult to work with and you only have a small area to work on.
    I'm new to the forum but have experience with using muriatic acid to clean calcium deposits, sometimes called hard water stain. JasonLion's suggestion is exactly what I would recommend. The white spots are not harmful, just unsightly.

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    Re: White substance on hot tub flagstone overflow & waterline tile

    I will try it when the weather warms up and post my results. Thanks
    Nov 2014 - 25,000 IG Freeform 3.5'-7' w/ 18" Spa, 7 Ton Rock Waterfall, Bordeaux PebbleSheen, UV & Corona Discharge Ozone, HC-3315 Chlorinator, Jandy CV580 Cartridge Filter, Jandy LXI 400K Heater, Polaris 280 Cleaner, Jandy LED Pool2 & Spa1, AquaLink PDA
    Jandy JEP2.0VS (Filter), Jandy SHPM2.5 (Spa), Jandy FHPM1.5 (Waterfall), Polaris PB4-60 (Booster) - 2006C

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    Re: White substance on hot tub flagstone overflow & waterline tile

    I did the suggestions above with Muriatic and water and it took it off my water line tile. Now i am seeing more and more of this coming from my grout above my water line tile and on the rock waterfall mortar and grout on the spa sillover tiles. None of it is on the waterline so i am doubting the CH level is too high. Does this mean that my CH is too high or would reducing the CH help control this? It is a fairly new pool of about 6 mths. My numbers which i feel are all in the correct ranges are below. Any suggestions on how to control this?

    CL 3
    PH 7.4
    TA 65
    CH 300
    CYA 50

    Pool Water Temp 82 degrees
    Nov 2014 - 25,000 IG Freeform 3.5'-7' w/ 18" Spa, 7 Ton Rock Waterfall, Bordeaux PebbleSheen, UV & Corona Discharge Ozone, HC-3315 Chlorinator, Jandy CV580 Cartridge Filter, Jandy LXI 400K Heater, Polaris 280 Cleaner, Jandy LED Pool2 & Spa1, AquaLink PDA
    Jandy JEP2.0VS (Filter), Jandy SHPM2.5 (Spa), Jandy FHPM1.5 (Waterfall), Polaris PB4-60 (Booster) - 2006C

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