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Thread: Swamp turning blue, algae on walls, TONS of chlorine!

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    Swamp turning blue, algae on walls, TONS of chlorine!

    My pump and pool vac broke so I've been getting them fixed the past couple weeks. In the meantime, my pool turned from blue with brown algae (assume this was mustard) on the sunny wall to a cloudy green swamp. Everything was fixed as of yesterday so I started working on the chemicals last night.

    I don't have a good test kit, just strips.

    Start (last night):
    FC - 1-2
    CC - unk
    pH - 8.2 (if I remember right?)
    TA - 100-120
    CH - unk
    CYA - a TON! - 150+
    Borates - unk

    I added 3/4 gal of acid, then 1092 oz of 6% bleach. About an hour later, the test strip showed FC super dark purple and CYA looked like it came down 90-100. I added 4 gallons of 10% liquid chlorine.

    In the morning it was still cloudy and very green (though a little less so). I brushed, backwashed a couple inches, and refilled the pool.

    On my test strip, FC was still super dark purple. I took a sample to the pool store and they tested:
    FC 3.0
    PH 7.6
    TA 100
    CYA 100+ (their test didn't go any higher)

    I thought maybe my test strips were old and bad and they gave me a new sample bottle. When I got home, I tested with the new strip and FC still showed super dark purple!

    In any case, I added 6 gallons of 12% liquid chlorine and 1 quart of acid. Tested 1.5 hours later and FC was still super dark purple. I added 4 more gallons of chlorine and left for the day.

    7 hours later, my pool is cloudy gray, very slight green tint, with brown algae on the steps/sides. I brushed, backwashed a couple inches, and am now refilling. Algae is not brushing off very easily, but better than it was.
    Latest test strip:
    FC: super dark purple
    PH: 8.4
    TA: 100
    CYA: 300?? The test strip shows a color this high and was pretty purple, but this seems crazy!

    I have 6 gallons of chlorine left right now. I can get more in the morning. I've added 3 quarts of acid already. Should I add more chlorine tonight?
    J.
    Phoenix - 16,500 gallon plaster diving pool, 1.5 hp pentair whisperflo pump (with 3/4 impeller), 3.1 sta-rite cristal flo sand filter, hayward ultra pool vac

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    JesseWV's Avatar
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    Apr 2011
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    North Central WV
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    Re: Swamp turning blue, algae on walls, TONS of chlorine!

    Quote Originally Posted by jperiod
    My pump and pool vac broke so I've been getting them fixed the past couple weeks. In the meantime, my pool turned from blue with brown algae (assume this was mustard) on the sunny wall to a cloudy green swamp. Everything was fixed as of yesterday so I started working on the chemicals last night.

    I don't have a good test kit, just strips.

    Start (last night):
    FC - 1-2
    CC - unk
    pH - 8.2 (if I remember right?)
    TA - 100-120
    CH - unk
    CYA - a TON! - 150+
    Borates - unk
    It would have been a good idea to drain and refill before adding chlorine since your CYA is so high.

    I added 3/4 gal of acid, then 1092 oz of 6% bleach. About an hour later, the test strip showed FC super dark purple and CYA looked like it came down 90-100. I added 4 gallons of 10% liquid chlorine.
    Strips do not accurately measure CYA levels especially when FC levels are high.

    I have 6 gallons of chlorine left right now. I can get more in the morning. I've added 3 quarts of acid already. Should I add more chlorine tonight?
    Don't add anymore chlorine until you drain at least 1/3 of your pool water and refill. Then get your CYA tested again. In the meantime try to get your hands on a good test kit like the TF-100 or Taylor K-2006. Both have the FAS/DPD chlorine drop test which will allow you to read the FC levels accurately at shock levels. Both will allow you to do your own CYA test as well.
    16k gal, 28'x3.5', Vinyl A/G, 1hp Pentair Dynamo 2-speed Pump, Hayward S160T Sand Filter, Intermatic HB800RCL Digital Timer, Intex 8110 SWG, TF-100 Test Kit, SpeedStir Author: Jesse's Graphical Pool Testing Log

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    benavidescj's Avatar
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    Apr 2010
    Location
    Fleming Island, FL
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    Re: Swamp turning blue, algae on walls, TONS of chlorine!

    What Jesse said.
    Carlos
    Pool: 28,000 gallons IG; IC 40 SWG; Pentair 120 gpm cartridge filter; Marble finish; Pentair Wisperflow 1.5 hp; Polaris 360
    Spa: 350 gallon; Bromine
    How to shock your pool

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    JasonLion's Avatar
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    Silver Spring, MD
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    Re: Swamp turning blue, algae on walls, TONS of chlorine!

    In addition to replacing water to get CYA down, it is also important to bring the PH down to something more around 7.5.
    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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    benavidescj's Avatar
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    Apr 2010
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    Fleming Island, FL
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    Re: Swamp turning blue, algae on walls, TONS of chlorine!

    Keep in mind that pH readings are inaccurate at high levels of FC. As Jason said you should have your pH around 7.5 when shocking but if you are currently at a high FC level your pH reading will be off. You will need to wait till the FC drops some to get an accurate reading.
    Carlos
    Pool: 28,000 gallons IG; IC 40 SWG; Pentair 120 gpm cartridge filter; Marble finish; Pentair Wisperflow 1.5 hp; Polaris 360
    Spa: 350 gallon; Bromine
    How to shock your pool

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    JesseWV's Avatar
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    Apr 2011
    Location
    North Central WV
    Posts
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    Re: Swamp turning blue, algae on walls, TONS of chlorine!

    Quote Originally Posted by JasonLion
    In addition to replacing water to get CYA down, it is also important to bring the PH down to something more around 7.5.
    It looks like he got his pH nailed before he started adding more chlorine. Of course now it's reading higher again because of the high FC.

    Quote Originally Posted by jperiod
    I added 3/4 gal of acid, then 1092 oz of 6% bleach. About an hour later, the test strip showed FC super dark purple and CYA looked like it came down 90-100. I added 4 gallons of 10% liquid chlorine.

    I took a sample to the pool store and they tested:
    FC 3.0
    PH 7.6
    TA 100
    CYA 100+ (their test didn't go any higher)
    I'm sure you would agree he definitely should test the pH again after the refill just to see where it's at before going through the shock process.
    16k gal, 28'x3.5', Vinyl A/G, 1hp Pentair Dynamo 2-speed Pump, Hayward S160T Sand Filter, Intermatic HB800RCL Digital Timer, Intex 8110 SWG, TF-100 Test Kit, SpeedStir Author: Jesse's Graphical Pool Testing Log

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