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Thread: Menacing Green Algae - Water's fine?

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    Menacing Green Algae - Water's fine?

    After a few days of on/off rain and a ~1 day depletion of FC, we started getting some green algae growth on the bottom of the pool. This is the first time we have seen algae since we set it up about two months ago. I super-chlorinated the pool using extra tabs in the floater as well as liquid chlorine and ended up adding about two lbs of A&H baking soda to get the numbers back in the normal range. Now that they have stayed in the ideal? range for several days, the green algae is growing again. I added around 3.5 oz of algaecide yesterday afternoon but no noticeable change this am (pump running 24/7 and keep filter checked/clean).

    Am I doing something wrong here?

    Numbers from yesterday evening:
    FC=5 | pH=7.4 | TA=120 | CYA=25 | Calcium Hardness=90 | TDS=500
    Tested the same numbers with home (HTH) test kit and Leslie pools in store testing.
    1.8K gal, AG, 530 gph Krystal Clear pump, "A" Filter Cartridge, set up spring 2013, NJ-USA

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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Menacing Green Algae - Water's fine?

    The ideal range for chlorine is not high enough to get ahead of the algae growth. You need to raise FC to Shock level to kill it fast enough to see a change.

    It should be relatively easy to clean it all up, if you have the right test kit.

    Rather than spend an hour typing up a response, I'll just refer you to a few threads that show the process. Since your pool isn't an evil swamp, it should go fairly fast; you're jumping in somewhere at the week mark. If any of the terms used in these threads confuse you, there's Pool School.

    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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    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Menacing Green Algae - Water's fine?

    Welcome to TFP.

    Assuming that you've read the ABC's of pool chemistry and how to SLAM your pool (if you haven't, go do that now), it's going to take more than one dose and/ or one day of SLAMing your pool to get it clear. At 1800 gallons it may be easier and quicker to drain, clean with bleach and refill.
    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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    Re: Menacing Green Algae - Water's fine?

    Thanks for the info guys.
    I have indeed been reading the Pool School info and did SLAM the pool, just not long enough I guess. Unfortunately, the test kits I have don't have the FAS-DPD test and I can't really tell how high my FC level is over the top of the Poolmaster 5 way kit's top line. I can tell you the FC level was a dark orange color (very scientific observation, I know). Aside from dropping $60 on the Taylor kit, can you guesstimate how long I should maintain SLAM FC level?
    1.8K gal, AG, 530 gph Krystal Clear pump, "A" Filter Cartridge, set up spring 2013, NJ-USA

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    Charlie_R's Avatar
    Join Date
    May 2013
    Mexico, MO

    Re: Menacing Green Algae - Water's fine?

    No way of knowing, other than until you can pass the Overnight Chlorine Loss Test (OCLT), which REQUIRES the FAS-DPD test.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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