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Thread: Help identifying this stain or deposit

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    Help identifying this stain or deposit

    Hi, can someone assist me in identifying and possibly removing this stain or deposit. Looks like possibly a calcium scale deposit, not sure. Here are a couple of pictures.

    The pool is a 20,000 gallon, salt water, gunite with diamond brite plaster.

    Thanks
    Attached Images Attached Images
    20k gal Gunite, diamond brite plaster, Jandy 340 cartridge filter, T-Cell 15 SWG, Jandy Stealth 1.5hp single speed pump, Polaris 280

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    Richard320's Avatar
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    Re: Help identifying this stain or deposit

    That looks like the beginnings of scaling. It looks like it has poor circulation in those areas.

    Can you post some test results? If you have high CH, TA, or pH, you're more prone to get it. The good news is, maintaining pH at the lower end of the acceptable range and brushing that area could dissolve it back into solution. In a space of months, if not years. But it worked for me.

    Also, play with you return eyeballs. See if you can't improve the water flow there.
    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.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Divin Dave's Avatar
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    Re: Help identifying this stain or deposit

    What Richard said about test ruslts would help a LOT.
    It sorta look like Calcium though.

    A couple different tests you can do.

    you can test it by putting chlorine tab on it. If the stain lifts, the stain is orgaic and should come off with a it of elevated FC and Time

    You can test it by putting a VItamin C tablet on it. If the stain lightens, then the stain is metal.
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    Re: Help identifying this stain or deposit

    Thanks, I'll post my test results tomorrow. It was completely white and then started turning a little brownish. Could very well be a water flow issue. It is on the opposite side of my steps from the filter return.
    20k gal Gunite, diamond brite plaster, Jandy 340 cartridge filter, T-Cell 15 SWG, Jandy Stealth 1.5hp single speed pump, Polaris 280

  5. Back To Top    #5

    Re: Help identifying this stain or deposit

    Okay, I had my water tested this morning and this is what they said.

    Total Chlorine 1
    Salt 2700
    Calcium Hardness 200
    Cyanuric Acid 30
    Total Alkalinity 90
    pH 7.6
    Phosphates 100

    Obviously I have a couple of issues to take care of, but do you guys think dropping the Phosphates and the pH a bit and just brushing is my plan of action with this deposit?
    20k gal Gunite, diamond brite plaster, Jandy 340 cartridge filter, T-Cell 15 SWG, Jandy Stealth 1.5hp single speed pump, Polaris 280

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    Re: Help identifying this stain or deposit

    Forget phosphates....irrelevant in your situation. Get your chlorine up to about 4 ppm pronto. Report the effects of the tests Divin Dave suggested. Put your City and State in your sig so we can suggest a CYA level (probably higher)

    I think that stain is a chemical "spill" wherein something like acid was poured directly into the pool and it sunk to the bottom. It could also be a stain that was deposited when the pool was empty. Still guesswork at this point but it may be permanent.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  7. Back To Top    #7

    Re: Help identifying this stain or deposit

    Okay, I had a different pool store test the water again today because I am not 100% sure I trust the first one. This is what they found

    TC 1
    pH 7.5
    TA 85
    Calcium Hardness 80
    Stabilizer 30
    Salt 2700

    The Calcium hardness came out way low. They thought this might be the cause of the stain. I adjusted the calcium, added stabilizer and shock.

    I also test the stain with vitamin C and chlorine tab as indicated above. No real change in color from either test.

    - - - Updated - - -

    Quote Originally Posted by duraleigh View Post
    Forget phosphates....irrelevant in your situation. Get your chlorine up to about 4 ppm pronto. Report the effects of the tests Divin Dave suggested. Put your City and State in your sig so we can suggest a CYA level (probably higher)

    I think that stain is a chemical "spill" wherein something like acid was poured directly into the pool and it sunk to the bottom. It could also be a stain that was deposited when the pool was empty. Still guesswork at this point but it may be permanent.
    Thanks, I am in Baton Rouge, Louisiana. I have been the only one to ever maintain the pool since new and I have never poured any chemicals in this location. The stain just appeared in the last month or two.
    20k gal Gunite, diamond brite plaster, Jandy 340 cartridge filter, T-Cell 15 SWG, Jandy Stealth 1.5hp single speed pump, Polaris 280

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    Mod Squad tim5055's Avatar
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    Re: Help identifying this stain or deposit

    It's time to get your own test kit from the list of recomended kits. Pool store testing is worth what you pay for it.

    The TF100 is the most recomended kit.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Help identifying this stain or deposit

    never poured any chemicals in this location.
    Well, since the stain is quite localized, it's hard to imagine an overall water condition (like low CH or low or high anything else) causing that in one concentrated spot. I can't think of any explanation other than a concentrated spill of some kind......especially since the tests for staining came back negative.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  10. Back To Top    #10

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    Re: Help identifying this stain or deposit

    Both of Dave's comments above are the best and most likely scenario. Even a powder like cyanuric acid, soda ash, dry acid, etc., can leave a stain like that.

    How old is the pool? Have you felt that area with your hand, and is it rough or sandpaper like? The surface could be etched or scaled.
    The roughness of the plaster could have been caused when new and before the pool was filled with water, and now has stained after time from dirt or metals in the water.

    As a remedy, try using 100 grit wet-or-dry sandpaper for a few minutes and see if it comes off. The sandpaper will also make the plaster surface very smooth.

  11. Back To Top    #11

    Re: Help identifying this stain or deposit

    Thanks for the suggestions. I haven't felt the spot yet, the water is still too cold. The pool is about 5 years old and and the stain just appears in the last month or two.
    20k gal Gunite, diamond brite plaster, Jandy 340 cartridge filter, T-Cell 15 SWG, Jandy Stealth 1.5hp single speed pump, Polaris 280

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