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Thread: Recurrent green algae

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    Recurrent green algae

    I have had my pool for 8 going on 9 years and have had no issues. In the last 6 months, I have had green algae over and over and over. Leaves don't sit in my pool, I maintain my chemcials and I have shocked more in the last 6 months than since I've owned the pool. The pool store has no answers except for that my water is old so I should replace. I drained my pool, started over with new water - same problem. I purchased the TF-100 test kit hoping that would give me some answers. I've read through a lot of the info, but it starts to get overwhelming. Recommended levels are listed for Vinyl, Plaster or Fiberglass. I have Pebbletech ???????? These are my readings: FC-4 TC-5 pH-7.5 T/A-100 CH-600 CYA-85 If you can help I would be so grateful!!!!!!
    14,000 gallon in ground pebbletech pool
    Purex Clean & Clear Plus 2hp pump - Hayward Navigator

    Test Kit TF-100
    Cave Creek, Arizona

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    Join Date
    Jun 2007

    Re: Recurrent green algae

    Smarter people will be by, but IMO:

    Your CYA level is high and your FC level is low for the amount of CYA you have. Without algae, you should be maintaining at 7-10 for FC with CYA of 85. Take a look at the chart in the pool school section for the recommended chlorine/CYA levels. For now, you have combined chlorine of 1 and algae, which means you should shock your pool. At CYA of 85, you will want to bring your chlorine level to 35.

    So you need to hit your pool with lots of bleach, run the filter 24/7, and brush thoroughly. Also, make sure you don't use stabilized chlorine, that will only increase your CYA.

    The only issue is whether your should do a partial drain first to try to reduce your CYA level before you attack the algae. The professionals here can answer that question.
    17K gallon in-gound pool, black plaster, Polaris 380, cartridge filter system

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Recurrent green algae

    PebbleTech is plaster, technically pebbles embedded in plaster. You treat it the same as you would any other plaster surface, though normally it will last much longer.

    Lowering your CYA level would make everything easier, though it isn't essential. More important is figuring out how your CYA level got so high this quickly after refilling. Trichlor pucks and dichlor granular shock both add CYA. If you don't stop using whatever it is that is raising your CYA level you will continue having problems.
    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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