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Thread: Stains in fiberglass pool

  1. Back To Top    #1

    Join Date
    Apr 2012
    Location
    Newton, NC
    Posts
    157

    Stains in fiberglass pool

    This is our third season for our fiberglass pool. The past 2 years, when we opened the pool, there were quite a few leaves in it. We got the leaves out, balanced the chemicals, and had clear water and a clean pool for the summer...no staining. This year, we opened the pool, got the leaves out and found that nearly 2/3 of the pool surface is stained...kind of a yellow/green/brown color. The staining is in all areas of the pool with patches of unstained areas. Brushing it does nothing.

    Test results after opening:
    TA 60
    CH 160
    CYA 25
    pH 7.1
    Salt 2200 (added 2 bags, now at 2900)

    At first I thought it was algae. I tested and found .5 CC...hardly a high reading, but I had always had 0 in the past. So, I got the chlorine up to about 11 and kept it there for a few days. The stains remained, but the CC was down to 0. So, I guess it's not algae.

    Over several days, I lowered the FC down to 1. Still had a CC of 0. I added 1.5 lbs of Stainfree a couple of hours ago. I have tried brushing and don't see any reduction in the stain.

    My current readings are:
    TA 80
    CH 200
    CYA 30 (keeping it low to get FC low for Stain Free)
    pH 7.2

    We have city water.

    I know I am supposed to vacuum 24 hours after putting in the Stainfree. I'll give it 24 hours to fight the staining. If the Stainfree doesn't work, I don't know what to try next.

    What could be the cause of the staining?
    Vince L

    16' x 37' fiberglass pool, 8' fiberglass spa, Hayward Swimclear C3030 filter, Hayward EcoStar VS pump, Goldline Pro Logic PL-PS-8, Goldline SWCG, Goldline Sense & Dispense pH control, Fiberstars LED's in pool & spa, AquaCal SQ175R heat pump, SR Smith Typhoon slide, Polaris 9300xi robotic cleaner, TF-100 Test Kit

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Stains in fiberglass pool

    Try placing a vitamin c tablet on one of the stained areas and see if that does anything.
    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

    Join Date
    Apr 2009
    Location
    Burlington, ON, Canada
    Posts
    337

    Re: Stains in fiberglass pool

    I've used Stain Free before - it's Citric Acid. If it's metal staining, you'll usually see it disappear right before your eyes when you add the product.
    16x28 Roman, 55000 litres, salt water, Zodiac Duoclear 130 (mineral cartridge removed!!!), inground, vinyl liner
    Hayward Tri-star VS900 (1.85 HP) pump, Hayward C3030 cartridge filter
    Nine Techno Solis 4x10 solar panels, Jandy LX 250 natural gas heater
    Jandy Aqualink PDA with Sub Panel Power Centre

  4. Back To Top    #4

    Join Date
    Apr 2012
    Location
    Newton, NC
    Posts
    157

    Re: Stains in fiberglass pool

    Quote Originally Posted by rcy View Post
    I've used Stain Free before - it's Citric Acid. If it's metal staining, you'll usually see it disappear right before your eyes when you add the product.
    While they don't list the ingredients, like you say, my understanding was that Stain Free is really just citric acid. I had figured (hoped) that I would see the stains just fade away right after adding it. But, after a couple of hours, I couldn't see any sign of the staining going away.

    Once the rain stopped about an hour ago, I followed JasonLion's suggestion of putting a Vitamin C tablet right on a stained area. I put a few Vitamin C tablets on a stained area, and there was a slow clearing of the stain around the tablets. So, I guess it is metal. Don't know why we have it this year and not in prior years.

    Now that it has been several hours since putting in the Stain Free, it seems that overall the stained areas have lightened a bit. Or, maybe that's just my eyes and my hopefulness playing tricks on me.

    I guess it's time to buy some ascorbic acid...quite a bit cheaper than Stain Free.
    Vince L

    16' x 37' fiberglass pool, 8' fiberglass spa, Hayward Swimclear C3030 filter, Hayward EcoStar VS pump, Goldline Pro Logic PL-PS-8, Goldline SWCG, Goldline Sense & Dispense pH control, Fiberstars LED's in pool & spa, AquaCal SQ175R heat pump, SR Smith Typhoon slide, Polaris 9300xi robotic cleaner, TF-100 Test Kit

  5. Back To Top    #5

    Join Date
    Apr 2012
    Location
    Newton, NC
    Posts
    157

    Re: Stains in fiberglass pool

    UPDATE

    It's been a bit over 24 hours since I added the Stain Free. I would say 90% of the staining is GONE!. I guess it just took a long time for the Stain Free to break up the staining.

    I ordered 5 lbs. of ascorbic acid yesterday. Hopefully, it will arrive on Friday or Saturday, and I can add some of it to eliminate the remaining stain.

    I am still baffled as to why we have had this staining this year. Nothing about the pool or pool equipment has changed in the past 2 years.
    Vince L

    16' x 37' fiberglass pool, 8' fiberglass spa, Hayward Swimclear C3030 filter, Hayward EcoStar VS pump, Goldline Pro Logic PL-PS-8, Goldline SWCG, Goldline Sense & Dispense pH control, Fiberstars LED's in pool & spa, AquaCal SQ175R heat pump, SR Smith Typhoon slide, Polaris 9300xi robotic cleaner, TF-100 Test Kit

  6. Back To Top    #6

    Join Date
    Apr 2009
    Location
    Burlington, ON, Canada
    Posts
    337

    Re: Stains in fiberglass pool

    That's good news. Don't forget to add metal sequestrant so the stains don't come back.
    16x28 Roman, 55000 litres, salt water, Zodiac Duoclear 130 (mineral cartridge removed!!!), inground, vinyl liner
    Hayward Tri-star VS900 (1.85 HP) pump, Hayward C3030 cartridge filter
    Nine Techno Solis 4x10 solar panels, Jandy LX 250 natural gas heater
    Jandy Aqualink PDA with Sub Panel Power Centre

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