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Thread: Algae Despite High Chlorine

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    Algae Despite High Chlorine

    Hi All,

    14000G plaster in ground pool. Intelliflow VS pump runs at 2100RPM from 8am to 9pm. Cartridge filter. Use TF100 (new test kit as of July).

    Went away on vacation and pool sitter let it get a little green. I SLAMed the pool two weeks ago when I got back and things were fine, but this week noticed a little green on the side in the corner. Chemistry is good:

    FC 7 (I have been keeping this a little high since the SLAM)
    TA 100
    CYA 40
    Calcium 300
    ph 7.5 (there is about average, but this is where it was this morning)
    Temp 80F

    Maybe I need to clean the filter better? Seems strange to get algae with the chlorine level above 7.
    -Ray

    14,000G, IG-Plaster, Pentair Clean&Clear Cartridge 200, Intelliflow VS 3050, 20+ year old, SunTouch Controller, Solar Heating

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    Mod Squad YippeeSkippy's Avatar
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    Re: Algae Despite High Chlorine

    You need to perform an OCLT (Overnight Chlorine Loss Test) to determine if there is anything organic in the water eating up your chlorine.

    Instructions for OCLT---> Pool School - Perform the Overnight FC Loss Test (OCLT)
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    Texas Splash's Avatar
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    Re: Algae Despite High Chlorine

    I agree with YS. And since we don't have the details of the previous SLAM (test readings, duration, validation of all 3 criteria passing, etc) it's difficult to know if ALL the algae was actually neutralized a couple weeks ago. If not, if there was ANYTHING remaining, that's how it came back. The OCLT will confirm if you have algae now, and if you do need to SLAM, just make sure you follow the Pool School - SLAM - Shock Level And Maintain to the letter. After that, "then" maintaining your target will be just fine. Remember:
    When performing the OLCT, remember that it must be done when the sun has dropped – no sunlight on the pool. About 8 hours total is recommended. Also, your FC level should be elevated more than normal. Starting (bedtime) FC could be close to your SLAM level, but no lower than 10. Anything less and you may not receive an accurate portrayal of FC loss (by percentage), even if it’s only 1 ppm.
    Best of luck to you!
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    PAGirl's Avatar
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    Re: Algae Despite High Chlorine

    Is it in an area that could have poor circulation? Do you brush the pool regularly?
    26' X 52" Intex Ultra Frame. Intex Sand Filter
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    You can lead a horse to (clear) water, but you can't force him to swim in it!

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    pabeader's Avatar
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    Re: Algae Despite High Chlorine

    I'm with PA on this one as to cause, sounds like circulation trouble in that corner.

    Repair is the same as always, SLAMing time!!

    Long term, is there a way to direct a return more into that corner?
    Bob - Palm Beach by San Juan Pools. approx 5000 gals., Pentair 320 cartridge filter (all new guts installed by me), Goldline SWG, 'New to me' Kreepy Krauly Sand Shark, Intermec 104 Timer Test kit: TF-100 w/Speed Stir

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    Divin Dave's Avatar
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    Re: Algae Despite High Chlorine

    +1. PAGirl hit the nail on the head.

    Corners are notorous for poor circulation and we should all brush our pools at least once a week. Even keeping our FC in check, if we dont have really good circulation and brush, its a likelyhood, that there will be minor bouts with algae sooner or later.

    Quote Originally Posted by PAGirl View Post
    Is it in an area that could have poor circulation? Do you brush the pool regularly?
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    Re: Algae Despite High Chlorine

    Thanks everyone! (a bit late on the response)

    OK, so I get it. I probably did not quite get it all last time. And yes, places where there are poor circulation. I brush the pool here and there but not as regularly as I should. I will SLAM it again.
    -Ray

    14,000G, IG-Plaster, Pentair Clean&Clear Cartridge 200, Intelliflow VS 3050, 20+ year old, SunTouch Controller, Solar Heating

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