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Thread: Dissolving pool coping

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    Join Date
    Feb 2016
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    Granada Hills CA
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    5

    Dissolving pool coping

    Hello people does anyone know what's going on with my pool coping. It's like acid is being socked up and it's dissolving the concrete coping. Have you ever seen anything like this? What's going on? How do can I stop it?

    Thank you all,
    20K Gallon Pebble tech In ground New 2016 Salt system Spa Pentair Heater Pump and Quad DE 60 Filter

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    Join Date
    May 2013
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    North East Ohio
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    Re: Dissolving pool coping

    So can you give us a few more details like age and how you add and who adds chemicals and if it's a salt or fresh water chlorinated pool

    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    JodieM's Avatar
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    Jul 2013
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    Brownsburg, IN
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    155

    Re: Dissolving pool coping

    Salt will eat at your concrete. Be sure when you put it in that you don't let any sit on the concrete, brush it away.
    Pool Built June 2018,
    16x32, 20K, IG vinyl,
    2 speed Jandy Pro Plus Pump, Jandy JS Sand Filter, Jandy Tru-Clear SWG,
    JANDY JXI POOL HEATER/260K BTU, Polaris 280 + Booster, TF 100 Test Kit

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    Dec 2012
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    Manassas Park, VA
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    Re: Dissolving pool coping

    Do you put any powdered shock or PH down in the pool? I have seen powdered shock leave small holes in flag stone before.
    25,000 gallon in ground white plaster- 1 1/2 HP Pentair SuperFlo pump - 60 sqft FNS DE filter (with FiberClear), 1999 Sundance Optima 850 hot tub.
    Manassas Park, VA

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    Re: Dissolving pool coping

    Thanks guys, I put in my own chemicals. When I put salt in it's always at the deep end and brush it off. The stains are at the edges of the coping. And then after a while it eats away the concrete. All of them are around the shallow end. A couple of times in the past I've put acid around the whole pool in the shallow and also with that do any harm? In general I have to add acid every week to my pool because I have raised spa I get a lot of air ration so my pH goes up. I keep my alkalinity around 110. and pH 7.2 - 7.8.
    20K Gallon Pebble tech In ground New 2016 Salt system Spa Pentair Heater Pump and Quad DE 60 Filter

  6. Back To Top    #6

    Re: Dissolving pool coping

    Since the effect is mostly along a grout line, I suspect that it's probably efflorescence.

    Is most of the effect along grout lines?

    Do you get a really wet ground at times?
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  7. Back To Top    #7

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    Re: Dissolving pool coping

    Yes, You are absolutely right it's all along the edges of the grout and it's on the side that gets wet a lot and stays wet a lot. And I also see this I think coming out of the concrete decking. But how does this eat away the concrete cement? How do I stop it? Is there a test to make sure it's really that?
    20K Gallon Pebble tech In ground New 2016 Salt system Spa Pentair Heater Pump and Quad DE 60 Filter

  8. Back To Top    #8

    Re: Dissolving pool coping

    I’m pretty sure that at least some of what you’re seeing is due to efflorescence. Water can saturate the concrete, grout etc and dissolve some of the minerals. They migrate to the surface and are deposited as the water dries.

    I would suggest that you try to control the water such that the area is not constantly wet.
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  9. Back To Top    #9

    Join Date
    Jun 2016
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    East Central MS
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    117

    Re: Dissolving pool coping

    I agree it's probably efflorescence and seems to be coming from your mortar joints. If you clean it off (can use a stiff bristled brush and water or surekleen and an acid brush), seal your coping and mortar joints with a silane/siloxane sealant and the problem might not return. Seal your deck while you are at it. The degradation may be due to salt damage as the water evaporates, but also if water is in the concrete and heats up, it will expand and can damage it as well.
    34K gal, 20'x40' IGP (backfilled and reinforced concrete block walls with concrete floor built mid-1970's; renovated 2017), PebbleSheen Arctic White plaster finish, Lotus Prisma Marine 1x2 glass waterline tiles, Indiana limestone coping, 1.5hp Hayward pump, Pentair Triton II TR100 sand filter, Pentair Intellibrite 5g color LED 120v Pool Light, Dolphin Supreme M400 robot, Stenner 45M1 pump, Pentair 320 chlorinator (to raise CYA only)

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