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Thread: Algae gone, but cannot maintain FC level

  1. Back To Top    #1

    Join Date
    Jun 2014
    San Antonio, TX

    Algae gone, but cannot maintain FC level

    So I am a newbie and had an algae problem. I only had a simple 4 part drop test and chlorine/ph/ta were all fine. I started reading on here and figured high cya was my problem for sure. I bought a test strip which was all I could find at the time for a cya test and thought it showed 100+ so I started making plans to empty at least half my pool. I then took a sample to the evil pool store and I got phosphated. To my surprise my cya is normal at 45 but my phosphates were very high. To give her credit, the evil lady at the pool store guessed correctly that I have dogs that swim and a lot of leaves that I battle often. So I used the phosaway she gladly sold me and then algaecide and slaming 4 hours after putting in the phosaway and instantly my water is crystal clear. Everything is great except I have added liquid chlorine twice now and it disappears very quickly. I have tried adding it at night but the next morning there is almost 0 chlorine. Is the phosaway or algaecide eating my chlorine? What else could it be if all my levels other than chlorine are normal now?

  2. Back To Top    #2
    bridgman's Avatar
    Join Date
    Mar 2014
    Bowmanville, ON Canada

    Re: Algae gone, but cannot maintain FC level

    Some pool chemicals will increase chlorine consumption until they are eaten up, but not sure about the specific ones you used.

    In general when people say "algae is gone but FC keeps getting used up" the algae isn't really gone, just reduced.

    Note that "fine" levels on most test kits are usually not fine. It's best if you can post actual ppm levels.
    Cedar hot tub, 680 US gallons - Snorkel wood-burning heater, canoe paddle, "offline" Intex 1000 GPH pump/filter with skimmer

  3. Back To Top    #3
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Algae gone, but cannot maintain FC level

    How do you know your levels are normal without a proper test kit? I would not trust any of the pool store results ... especially for CYA.
    Jason, TFP Moderator
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  4. Back To Top    #4
    Beens's Avatar
    Join Date
    Jul 2013
    Virginia Beach, Va

    Re: Algae gone, but cannot maintain FC level

    Unfortunately the pool store tests are about as reliable as the test strips!

    The absolute best thing you can do is get one of the test kits we recommend here and with the results from that kit we can tell you exactly what it means and what your pool needs. We'll help and teach and you'll learn along the way!

    It is a heck of a lot better and more reliable than what you'll get from the pool store. (and less expensive because you won't be buying stuff you don't need that may or may not help!)

    The pool store lady is not evil. We don't think they're evil around here. Sometimes they're uninformed. Sometimes they don't care. Sometimes they've learned everything they know from the people supplying the store with the expensive chemicals they want to sell more of. It's just a shame because we see it every day, several times. People who have spent hundreds to thousands of dollars on "stuff" and still have problems with their pools!

    It's just best to test your own water with a test kit you can trust. A little kit that shows your chlorine in yellow and ph in shades of pink and yellow and orange is handy sometimes but more accuracy and more tests are needed to really know what's going on and exactly what you need to do to fix a problem!

    It looks like you've done some reading and started to understand what might be going on with your CYA level.

    Here's the thing, you are wondering if it could be the phosphate stuff or the algaecide consuming more of the chlorine. I'll add another thing it could could be that the CYA test that the store did was totally wrong and you need a lot more chlorine! You can't just guess and throw more in just in case because then you could damage something.

    So we're back to........needing reliable accurate test results.

    If you get a kit you'll use it. You won't regret it.
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  5. Back To Top    #5

    Join Date
    May 2013
    Bay City, Michigan

    Re: Algae gone, but cannot maintain FC level

    Quote Originally Posted by astuber View Post
    Everything is great except I have added liquid chlorine twice now and it disappears very quickly. I have tried adding it at night but the next morning there is almost 0 chlorine.
    Since chlorine is consumed by only 2 things....Organics like algae or bather waste, and from sunlight. If you lost all your chlorine over night...that says it all. It is likely that you have not gotten rid of ALL of the algae, you just removed enough of it to get clear water, and are using just enough chlorine to keep it at bay...but it's still there. You need to SLAM untill you pass the OCLT then your chlorine will start holding. To slam you will need to have the FAS-DPD chlorine test (for it's accuracy and ability to test high chlorine levels.
    12500 gallons, 24 foot round above ground
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    Kiss4aFrog's Avatar
    Join Date
    May 2013
    Hudson, WI

    Re: Algae gone, but cannot maintain FC level

    You might also want to pull the ladder if you have one and scrub and rinse it out of the pool, including the underside of the steps and if you have light(s) pull it/them and make sure there isn't anything green back there too.
    Are you sweeping the walls and floor daily ??

    This is what you need to do:

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