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Thread: Rust Stain Removal/Ascorbic Acid Questions

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    Join Date
    May 2013
    Location
    Norfolk County, MA
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    5

    Rust Stain Removal/Ascorbic Acid Questions

    Hi all. So I discovered this site 2 years ago (have had a pool for about 5 years) and did a lot of reading (but no posting) and learned so much. I have been using pool school and pool math ever since then to keep our pool in pretty decent shape. Here is my current situation:

    We have a big rust stain in our shallow end that has been there since we bought the house. A couple of years ago the pool was drained to replace the tile and coping and we had them try to see if they could etch it out if it was a surface stain. Unfortunately it is clearly coming from within the pool so it actually looked worse after that. We realize the real solution is to cut in and fix the problem from underneath (probably rebar causing it). Our plaster is old and will need to be refinished soon and we will fix this at that time. In the meantime….I researched on here and decided to see if I could improve the appearance of this with the ascorbic acid treatment. Especially since last year I noticed more staining on our walls that I thought might be caused by this.

    I did the treatment with ascorbic acid in a sock over the area plus spread around sides of pool. Definite improvement. The main stain is still there but the surrounding areas where it had "spread" are totally gone. My mistake was (I think) that I didn't add sequestrant fast enough. There was a good full day that passed before I managed to get some. Now the stain is still better but I feel like there are stains along walls in other areas of my pool. So my question is - do I need to repeat the whole ascorbic acid treatment now or can I just add more sequestrant to fix this?

    Also, how long do we have to wait to swim after adding either ascorbic acid or sequestrant? I added the ascorbic acid about a week ago and have had trouble keeping chlorine in the pool ever since starting to bring it back up but have stayed on top of it as best as I can - testing and adding twice a day. I think from what I've read that this is normal but just wanted to make sure? We swam yesterday after I had made sure chlorine levels and pH were ok but now if I need to add more how long do I need to wait again? AND, we JUST added a gas heater to our pool that was up and running two days ago. pH has been right at 7.2 (per instructions), do I need to start bringing it up more? I definitely don't want to damage the new heater. I'm starting to feel a little in over my head as I don't know what the best thing to do from here is. Any advice would be greatly appreciated! Since I'll probably be asked, here are current parameters (from Taylor K-2006):

    FC: 0.2 (already added more based on pool math)
    pH: 7.2
    TA: 70
    CH: 200 (started at 100 this season and have been adding to bring up)
    CYA: 40
    ~20K gallon IG gunite pool w DE filter & 400K BTU gas heater

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
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    Jun 2009
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    SouthWest Alabama
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    Re: Rust Stain Removal/Ascorbic Acid Questions

    It would be worth a try to add more sequestrant and see if it lightens the stains. If it doesn't you really haven't lost anything and if it does, you won't have to run the AA treatment again.

    As for when to swim. When it's clear and will hold some FC.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Join Date
    May 2013
    Location
    Norfolk County, MA
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    Re: Rust Stain Removal/Ascorbic Acid Questions

    OK, thanks. Pool finally seemed to be holding FC again - no loss overnight so I went ahead and let kids swim today. Water has been clear pretty much this whole time with the exception of right after doing the treatment. I think I will wait till the weekend is over and then try more sequestrant Sunday evening or Monday morning and see if that helps. How much more do you think I should add?
    ~20K gallon IG gunite pool w DE filter & 400K BTU gas heater

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    Swampwoman's Avatar
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    Apr 2012
    Location
    Grand Rapids, MI
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    Re: Rust Stain Removal/Ascorbic Acid Questions

    If you decide to use Metal Magic sequestrant, there are instructions to perform a "sponge test" on stained areas whereby it then tells you how high to dose according to how long it took to lighten the stains.

    So in my pool, for example, 2 quarts would be a normal startup dose for the season. But after dong sponge test, suggested application are was actually 5 quarts. At tat level it actually removed iron staining in my case as well as serving its primary role as sequestrant. This enabled me to bypass AA treatment and the FC battle that follows

    BUT your mileage may vary. Since you eed sequestrant anyway, seems like it might be worth a shot.

    Here's the instructions: http://www.proteampoolcare.com/image...SpongeTest.pdf

    Here's where I personally get my MM shipped from - decent price at 15.70 per qt, free shipping on a case: ProTeam Metal Magic (1 qt) offered by Pool Geek

    Let us know if that works for you if you decide to try it.
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
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    Join Date
    May 2013
    Location
    Norfolk County, MA
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    5

    Re: Rust Stain Removal/Ascorbic Acid Questions

    Great, thank you. I think I will try that. I couldn't believe how fast my chlorine was getting used up after doing the ascorbic acid treatment so if there was a way to avoid that it's worth a shot! I will try to get my hands on some Metal Magic and see if it does the trick!
    ~20K gallon IG gunite pool w DE filter & 400K BTU gas heater

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