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Thread: Need help with etching clean up

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    Need help with etching clean up

    Hi all, new here and could use some help with preparing my pool for use again.

    I had a problem last year and my SWG went out. Algae set in badly before we realized what was going on. Using shock and algicide several times to clean up, I believe caused some drastic etching. I eventually replaced my SWG controller and cell to produce chlorine again. We had these buildups on the bottom of the pool that did not want to clean up.

    I ended up draining the pool last week. (the water table is low, we have a ditch behind our house and is safe for now) What a nasty mess it was on the marcite lining. There was buildups some 1/4" high of green slime. I expect it to be from metals when using the algicide and plain ignorance of pool maintenance. We scraped most ot it off and now the marcite is etched in many places along the bottom of the pool. We tried using soft scrub to clean more and remove the discolorations and had no luck.

    The next thing I did was to put water in the pool and added about 1.2 Lb of United Chemical "Pool Stain Treat Sequestrant & chelator" (oxalic acid). I only added water to just hit the wall in the shallow end. Deep end is 5' and shallow end is 3'. The directions guide me for 2Lbs per 20K gallons. I know I am much higher percentage, trying to clean it up. It has been sitting there now for several days. I thought about draining it and doing a muratic acid wash of a 50% solution. But I have read some things that scare me from doing that.

    What can I do to make these stains less noticible ?



    Thanks in advance,
    Mike
    Attached Images Attached Images
    16X32 IG gunite pool w/ marcite
    AquaRite SWG
    15K gallons
    Pentair Triton II sand filter w/ SM10-3 valve
    Sta-Rite pump w/ 1.5HP single speed pump

  2. Back To Top    #2
    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: Need help with etching clean up

    That sounds like organic staining. If so, a couple of days at shock level will clear it up. However, it would also involve calcium scaling, which is tricker to deal with, but that seems less likely.
    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

  3. Back To Top    #3

    Re: Need help with etching clean up

    The marcite is actually pitted also where all of these build ups were at. Whatever we had going on, ate at the lining also.

    Am I hurting anything with the oxalic acid in there soaking away at the stains? I am thinking they may have lightened up. I have a very high concentrate of it compared to the small amount of water in the bottom of the pool.

    Should I add some shock to the water maybe ?

    The label does say to not add the acid directly to an oxidizer, but to add directly to a pool/spa. I am thinking that adding shock would not cause adverse reactions.



    Thanks Jason,
    Mike
    16X32 IG gunite pool w/ marcite
    AquaRite SWG
    15K gallons
    Pentair Triton II sand filter w/ SM10-3 valve
    Sta-Rite pump w/ 1.5HP single speed pump

  4. Back To Top    #4
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Need help with etching clean up

    You don't want to use either chlorine or stain remover without water in the pool and the pump running. The only exception would be using acid to remove calcium scaling while the pool is drained, but you seem fairly confident that isn't the issue. The stain remover is an acid and can damage the pool surface if used at a high concentration.
    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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