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Thread: Persistent Algae

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    Join Date
    May 2014
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    Persistent Algae

    First post. Just received the TF-100 test kit yesterday revealing some troubling numbers:

    FC 6.5
    CC 0
    pH 8.2
    TA 240
    CH 975
    CYA 120 (the cylinder is calibrated only to 100 - my estimate)

    I would like to SLAM to get rid of some low level but persistent algae, but suspect it would be difficult with these numbers, especially CYA and am looking for suggestions.

    In spite of the algae, water is basically clear.

    Thanks for your help. Great site.
    Keith

    25,000 gallon, 40' x 15', IG gunite built 1964, original plaster stripped and re-plastered/pebbled in 2012, 36 Sq. Ft. DE filter, 1 HP, original 80 GPM brass pump is going strong

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    Mod Squad jblizzle's Avatar
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    Re: Persistent Algae

    Welcome to TFP!

    You can start the cya test with half pool water and half tap water, then the reagent and do the test out side in bright indirect light with tube at your waist. Then double the reading to get a better idea of the CYA level.

    Then you need to replace water to get the CYA back in range if you hope to keep the pool clear.

    That CH is also very high and needs to come down, also by replacing water. With that high pH and TA, calcium scaling likely.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Casey's Avatar
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    Re: Persistent Algae

    You're going to need to do a few drain/refills to bring the CYA down.
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

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    Richard320's Avatar
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    Re: Persistent Algae

    You really have no choice but to drain a bunch of water. It looks like the wells near Burbank run about 90 feet, so I doubt there will be any danger of floating the pool.

    The good news is, now that you have a kit and some understanding, algae will be a thing of the past. Too bad you had to pick a drought year to get algae. Pump what uou can onto your lawn. The neighbors lawns, too. Better than just sending it all down the drain.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Persistent Algae

    Thanks Jason, Casey and Richard for your comments and ideas.

    Repeated the CYA test with half tap/half pool water and doubled, a good idea. Got the same number....60 x 2=120. It is a bit subjective so had my wife try and she also landed at about 120.

    So my next question is: How much of the 25,000 gal would you recommend that I drain?

    BTW, my wife just checked the current Burbank rates and 15,000 gal (for example) is looking like about $60.

    Yes, bummer to have to do this in a drought!
    Keith

    25,000 gallon, 40' x 15', IG gunite built 1964, original plaster stripped and re-plastered/pebbled in 2012, 36 Sq. Ft. DE filter, 1 HP, original 80 GPM brass pump is going strong

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    Mod Squad jblizzle's Avatar
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    Re: Persistent Algae

    If you have no ground water concerns, then you want to replace about 2/3 of the water to lower the CYA to about 40ppm.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: Persistent Algae

    As suggested, we drained about 2/3 of the water and replaced with the city of Burbank "blend". I noted that my local water registers CH at 325 and TA of 180 with a ph around 8.2.

    With the refill complete, I SLAMmed and passed the OCLT.

    Before I get to the question, here are the current numbers:

    CYA: 52
    ph: 8.2+ (a bit high, I know)
    CH: 650
    TA: 210

    We have been using 10% liquid chlorine ONLY to attempt to maintain a target FC of 7. Have not used any other chlorine products.

    What we are noticing is that we consistently drop to FC of around 3 on a daily basis. Is this normal? This has been going on for a couple months. Seems like we are using quite a bit of chlorine to keep this 25,000 gal within the acceptable range.

    The CC is always below .5, many times at 0.

    Thanks for all your help.
    Keith

    25,000 gallon, 40' x 15', IG gunite built 1964, original plaster stripped and re-plastered/pebbled in 2012, 36 Sq. Ft. DE filter, 1 HP, original 80 GPM brass pump is going strong

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    Mod Squad tim5055's Avatar
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    Re: Persistent Algae

    You have a good sized pool and 2ppm loss per day is not unheard of.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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