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Thread: Black and green algae keep on coming back

  1. Back To Top    #1

    Join Date
    Jun 2016
    phoenix, AZ

    Black and green algae keep on coming back

    So a little background, I have a 25000 gallon pool and spa. One of the issues in the pool that I believe causes a lot of problems is that there is no popups in the water other than on the stairs so the water does not circulate much even if the vaccum is on and running in the pool. For the past 6 months, I have been getting both black and green algae and they continuously keep coming back. I keep chlorine in the floater at all times but I don't think it works well enough. I typically go to my pool store (Leslies), which I know is usually a mistake, for advice and I am told to scrub the black algae with a chlorine tablet whenever it shows up and then shock the pool, which works for a couple weeks and then spots start showing up again within a couple weeks and I typically treat the green algae with shock and brushing. the pool store hasnt been much help as they tell me I need to buy like $200 of phosphate remover every time I go and my problem would be solved, which I don't believe is true.

    What would be the best way to approach this problem? I have test strips that I use to check the levels and I have just shocked the pool and scrubbed all the black algae spots. It is getting reaaally annoying having to spend so much time trying to get rid of this algae.

    Any help would be greatly appreciated.

  2. Back To Top    #2

    TFP Guide
    YippeeSkippy's Avatar
    Join Date
    Jan 2012
    'burbs of Augusta, Georgia

    Re: Black and green algae keep on coming back

    Welcome! Glad you found us. We're a very large group of volunteers who love helping others with their pools as we were once helped.

    If you have all those repeated problems it boils down to you not having enough FC in the water, you probably have far too much CYA stabiizer (it comes with puck and granular chlorine products) and your test strips are basically "Guess-Strips".

    Short and sweet answer is to get your own *reliable* test kit (and in a pool in AZ your size I would say the TF-100) from or You're going to need to perform testing far more precise than what the pool store or strips will give you.

    Bring your test results back to us and we'll help you tweak and fix your problems. We have a lot of members who live in AZ and are aware of some of the problems out there such as hard water, temps, etc. I'm sure one of them will jump in and offer help too.

    After you get your test kit please tell us:
    12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub. Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain
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  3. Back To Top    #3

    TFP Guide
    needsajet's Avatar
    Join Date
    Jan 2016
    Sydney, NSW, Australia

    Re: Black and green algae keep on coming back

    Welcome to TFP, great to have you here

    If you're wondering how things work, here's a couple of recent threads that tell the story. Not a must by any means, but if you have to time to scan through them, you might find it helpful.
    Need some help ASAP - a 9 year old's birthday party depends on it!!
    There are no shortcuts; believe in the process and trust the experts - thank you TFP

    There are at least 1,000 threads here that start out with stories just like yours, and TFP can help you achieve a safe, sparkly pool that may never turn green again - without the pool $tore.
    12k IG salt; glass beads in plaster; K-2006C, K-1766 Salt, CCL, and Aussie 4in1 (HTH); Pentair Eco800 VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Pentair Rebel pool cleaner; FlowViz flow meter; prior pool AG 10k - Be Safe - FC / CYA Chart - Become a TFP Supporter - Read Before Posting

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