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Thread: Chlorine and Algae problems

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    Join Date
    Jul 2011
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    Edwardsville, IL
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    Chlorine and Algae problems

    We bought our house last year and my project has been our pool. It seems I'm failing. I bought the test kit (TF-100) as suggested on this site and here are my readings:

    FC - 0 (didn't even turn pink when I put the powder in)
    CC - .5
    PH - 7.5
    TA - 120
    CH - 170
    CYA - 30

    When we opened the pool this year, we had some yahoo do it. He incorrectly told us how to maintain a DE filter and we have since been doing it correctly. After backwashing and fixing the DE issue I was able to have a good chlorine level. It dropped off quickly and I have never been able to keep the chlorine level up. I had my husband try the backwashing trick again to no avail. The water has been clear and only slightly aqua at times, but a dose of chlorine (granular) it would go away. However, the bottom of the pool in the shallow end (where it becomes shaded quicker) has black spots (black algae?) I'm guessing algae is our problem with the chlorine (not sunlight) and I have not chlorinated it enough initially or correctly (bleach). Please help. I'm new to this but will follow your instructions and re-read and re-read all the Pool School stuff I need to. I really appreciate the help!

    Sherry
    19,700 gallons
    DE filter
    IG
    Fiberglass side, concrete bottom

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    Mod Squad Bama Rambler's Avatar
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    Re: Chlorine and Algae problems

    Add enough to get you to 5 or 6 ppm and test in an hour to see if it holds.
    Tonight add enough chlorine to get to 6 and test it after the sun goes down and run the OCLT tonight to see what's going on. I'm pretty sure it's going to need shocking.
    Post back tonight's and tomorrow morning's readings and we'll help clear this up.
    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

  3. Back To Top    #3

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    Edwardsville, IL
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    Re: Chlorine and Algae problems

    Here's my numbers at night:

    FC - .5
    CC - 1.5
    PH - 7.5
    TA - 120
    CH - 170
    CYA - 30

    And in the morning:

    FC - 0
    CC - 1
    PH - 7.5
    TA - 120
    CH - 170
    CYA - 20

    I'm assuming shock time? Any other tips?

    Again, thanks so much for your help!!

    Sherry
    19,700 gallons
    DE filter
    IG
    Fiberglass side, concrete bottom

  4. Back To Top    #4

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    Aug 2010
    Location
    Boston, MA
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    Re: Chlorine and Algae problems

    Was that really 0.5 in the evening, or 5.0? If the former, then you didn't have enough to start with for a proper OCLT - as Bama said, get it up to 5-6 for the starting point. If the latter, you lost 4.5 ppm and definitely need to shock, esp. combined with 1.5 ppm CC.
    20k gallon IGP
    Plaster over gunite
    3/4 hp Hayward pump
    Purex Triton DE filter
    TF100 test kit w/ speedstir

  5. Back To Top    #5

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    Edwardsville, IL
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    Re: Chlorine and Algae problems

    It was .5. After attempting to get to 6 the chlorine wasn't holding. Do I need to shock to try and get me up to the right level then do the overnight loss test?
    19,700 gallons
    DE filter
    IG
    Fiberglass side, concrete bottom

  6. Back To Top    #6

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    Aug 2010
    Location
    Boston, MA
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    Re: Chlorine and Algae problems

    Do you mean that you add a couple gallons of bleach, test half an hour later, and the FC reads 0.5?
    20k gallon IGP
    Plaster over gunite
    3/4 hp Hayward pump
    Purex Triton DE filter
    TF100 test kit w/ speedstir

  7. Back To Top    #7

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    Edwardsville, IL
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    Re: Chlorine and Algae problems

    Yes. Adding 300ish oz of bleach did little after an hour (was 0) and brought to .5. Added 245 oz after that (per pool calculator) and no increase. Then let sit overnight.
    19,700 gallons
    DE filter
    IG
    Fiberglass side, concrete bottom

  8. Back To Top    #8

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    Boston, MA
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    Re: Chlorine and Algae problems

    Definitely sounds like you need to shock, but with it getting consumed THAT fast you're probably going to need a lot of bleach.
    20k gallon IGP
    Plaster over gunite
    3/4 hp Hayward pump
    Purex Triton DE filter
    TF100 test kit w/ speedstir

  9. Back To Top    #9
    Mod Squad Bama Rambler's Avatar
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    SouthWest Alabama
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    Re: Chlorine and Algae problems

    Ditto on the lot of bleach. And you need to test and add every hour until you start holding FC.
    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

  10. Back To Top    #10

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    Edwardsville, IL
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    Re: Chlorine and Algae problems

    I'm on day 2 of shocking and while I failed the overnight test last night (FC 11, night; FC .5, morning), my intervals of adding boatloads of bleach are going down, so I'm hopeful. I know this is going to take a bit more time, but I was wondering if anyone can identify the black spots on the bottom of my pool (see pic). I'm assuming algae and eventually the bleach will kill this off. Is this a safe assumption??
    Attached Images Attached Images
    19,700 gallons
    DE filter
    IG
    Fiberglass side, concrete bottom

  11. Back To Top    #11
    frogabog's Avatar
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    Jul 2010
    Location
    Portland, Oregon
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    Re: Chlorine and Algae problems

    Have you tried brushing them?
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

  12. Back To Top    #12

    Join Date
    Jul 2011
    Location
    Edwardsville, IL
    Posts
    6

    Re: Chlorine and Algae problems

    Yes, I've always brushed regularly. Did about 5 times yesterday. Once today. It's not moving or even flaking a bit.
    19,700 gallons
    DE filter
    IG
    Fiberglass side, concrete bottom

  13. Back To Top    #13
    frogabog's Avatar
    Join Date
    Jul 2010
    Location
    Portland, Oregon
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    Re: Chlorine and Algae problems

    I think you can try rubbing a chlorine tablet on it. If it fades, it's algae.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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