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Thread: Pool Balanced but still have Green Algae

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    Pool Balanced but still have Green Algae

    I tested the pool on Friday - everything was all in balance. Why do I still get green algae on the north facing wall of my pool? I've cleaned my cartridge filter twice this month hoping that would help. I keep it brushed off as soon as I see it. I have natural rock that touches the water on that side of the pool. Could there be some sort of algae that is seeping out of the rocks? The green starts at the surface of the water then grows downward. Water is crystal clear and beautiful. I'm using the last of my tri-clor tablets then going to the bleach method.

    FC 2
    TC 2
    CC 0
    TA 130
    ph 7.8
    CYA 35
    CH 420

    Thanks!
    17,000 gal. inground pool, Diamond Brite cool blue, Kreepy Krauly Legend inground pool cleaner(w/seperate pump), Pentair Clean & Clear Plus cartridge filter (420sq.ft), Pentair IntelliFlo vs-3050 variable speed pump, Pentair Rainbow model 320 chlorine feeder, Pentair IntelliBrite 5g LED lights (2), waterfall and 32 ft. of weeping wall (w/seperate pump), 2 skimmers, 4 drains, tanning ledge w/2 geisers, Jandy EE2500TI Heat Pump

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    gboulton's Avatar
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    Re: Pool Balanced but still have Green Algae

    To my inexperienced eye, I'd wager it's because you don't have enough chlorine to kill off existing algae.

    I suggest:

    Shock the pool according to the directions here.

    I'd also advise a higher post-shock FC level, in the 4-5 range, as suggested here.

    =======

    By all means, chime in experts if I've missed anything, or misled the OP!
    -Gordon
    Pool School helps me maintain my 13,500G 24' x 48" ASP with Sand Filtration using a TF100 Test Kit and Pool Calculator.
    Remember, the Shock Process should be followed until : 1. CC is less than 0.5 ppm, 2. An OCLT shows a loss of 1.0 ppm or less and, 3. The water is crystal clear.
    --I didn't buy my pool to swim in it. I bought my pool to watch my wife swim in it. :wink:

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool Balanced but still have Green Algae

    It's definitely because you don't have enough chlorine.

    Is it growing on the shady side of the pool? If so it's probably mustard algae.
    Is that an area of poor circulation?

    Have you ran an OCLT (see sig if you don't know what that is)?
    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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    maxepr1's Avatar
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    Re: Pool Balanced but still have Green Algae

    I would question your test kit. If you have visible algae you have to have some CC? You shouldn't be able to pass a OCLT.
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


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    Mod Squad JohnT's Avatar
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    Re: Pool Balanced but still have Green Algae

    Quote Originally Posted by maxepr1
    If you have visible algae you have to have some CC? .
    Not in my experience. I never see CC from algae.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Pool Balanced but still have Green Algae

    The instructions for shocking the pool says to add some chlorine until you reach the shock level (which according to the chart I am aiming for a 16). How much is "some?" Should I start with 1 gallon, 5 gallons? etc. I tried to use the pool calculator - entered the current FC at 2 and goal at 16, but when I hit the calculate button, nothing happens. I have searched the board looking for this answer but can't find a clue as to how much to start with. Help!
    My test kit is the leslies total poolcare DPD Test Kit. They didn't have the recommended one. I need to order it.
    Thanks!
    17,000 gal. inground pool, Diamond Brite cool blue, Kreepy Krauly Legend inground pool cleaner(w/seperate pump), Pentair Clean & Clear Plus cartridge filter (420sq.ft), Pentair IntelliFlo vs-3050 variable speed pump, Pentair Rainbow model 320 chlorine feeder, Pentair IntelliBrite 5g LED lights (2), waterfall and 32 ft. of weeping wall (w/seperate pump), 2 skimmers, 4 drains, tanning ledge w/2 geisers, Jandy EE2500TI Heat Pump

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    JasonLion's Avatar
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    Re: Pool Balanced but still have Green Algae

    4 1/2 gallons of regular 6% bleach to raise FC from 2 to 16 in 17,000 gallons. Remember that none of the common jugs are exactly a gallon.
    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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    Re: Pool Balanced but still have Green Algae

    Thank you! How did you figure that out?
    17,000 gal. inground pool, Diamond Brite cool blue, Kreepy Krauly Legend inground pool cleaner(w/seperate pump), Pentair Clean & Clear Plus cartridge filter (420sq.ft), Pentair IntelliFlo vs-3050 variable speed pump, Pentair Rainbow model 320 chlorine feeder, Pentair IntelliBrite 5g LED lights (2), waterfall and 32 ft. of weeping wall (w/seperate pump), 2 skimmers, 4 drains, tanning ledge w/2 geisers, Jandy EE2500TI Heat Pump

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    Smykowski's Avatar
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    Re: Pool Balanced but still have Green Algae

    Quote Originally Posted by momtaps
    Thank you! How did you figure that out?
    Did you put your pool size in before you started?
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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    Re: Pool Balanced but still have Green Algae

    I had entered 17,000. When I removed the comma - 17000, it worked. Thanks so much for everyone's help.
    17,000 gal. inground pool, Diamond Brite cool blue, Kreepy Krauly Legend inground pool cleaner(w/seperate pump), Pentair Clean & Clear Plus cartridge filter (420sq.ft), Pentair IntelliFlo vs-3050 variable speed pump, Pentair Rainbow model 320 chlorine feeder, Pentair IntelliBrite 5g LED lights (2), waterfall and 32 ft. of weeping wall (w/seperate pump), 2 skimmers, 4 drains, tanning ledge w/2 geisers, Jandy EE2500TI Heat Pump

  11. Back To Top    #11

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    Re: Pool Balanced but still have Green Algae

    OK, I got my new test kit TF100 in the mail today and began the process of shocking my pool. According to the pool calculator, with today's test results, I needed to add 2.1 jugs of bleach to raise the FC from 5 to 16. I did this, waited an hour, and tested again. I am at 20.5 now! Is that OK? I am shocking because of algae.

    CYA 40
    FC 5 (before shocking with chlorox 6%)
    CC 0
    TC 5
    TA 80
    ph 7.5
    17,000 gal. inground pool, Diamond Brite cool blue, Kreepy Krauly Legend inground pool cleaner(w/seperate pump), Pentair Clean & Clear Plus cartridge filter (420sq.ft), Pentair IntelliFlo vs-3050 variable speed pump, Pentair Rainbow model 320 chlorine feeder, Pentair IntelliBrite 5g LED lights (2), waterfall and 32 ft. of weeping wall (w/seperate pump), 2 skimmers, 4 drains, tanning ledge w/2 geisers, Jandy EE2500TI Heat Pump

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    linen's Avatar
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    Re: Pool Balanced but still have Green Algae

    Quote Originally Posted by momtaps
    OK, I got my new test kit TF100 in the mail today

    Quote Originally Posted by momtaps
    According to the pool calculator, with today's test results, I needed to add 2.1 jugs of bleach to raise the FC from 5 to 16. I did this, waited an hour, and tested again. I am at 20.5 now! Is that OK?
    That is fine. How sure are you of your pool volume?

    Quote Originally Posted by momtaps
    CYA 40
    FC 5 (before shocking with chlorox 6%)
    CC 0
    TC 5
    TA 80
    ph 7.5
    The rest of you numbers look good! Have you measured CH yet?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  13. Back To Top    #13

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    Re: Pool Balanced but still have Green Algae

    Just tested the ch - 3 times with 3 different results!

    Leslies kit - 410
    TF100 - 800 1st time, 650 2nd time

    What's up with that?
    17,000 gal. inground pool, Diamond Brite cool blue, Kreepy Krauly Legend inground pool cleaner(w/seperate pump), Pentair Clean & Clear Plus cartridge filter (420sq.ft), Pentair IntelliFlo vs-3050 variable speed pump, Pentair Rainbow model 320 chlorine feeder, Pentair IntelliBrite 5g LED lights (2), waterfall and 32 ft. of weeping wall (w/seperate pump), 2 skimmers, 4 drains, tanning ledge w/2 geisers, Jandy EE2500TI Heat Pump

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool Balanced but still have Green Algae

    Are you using a speedstir? If not I'm not surprised at the variance. The CH test is very hard to do repeatedly by hand swirling.
    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
    Pool School ----- Pool Math ----- TF-Test Kit

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