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Thread: Algae is starting to come back

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    Algae is starting to come back

    I did a bleach shock treatment on our pool about three weeks ago and the water was clear with no visible signs algae. When performing the shock the FC was holding at 23 at night so I let the FC level drop to 11 then the algae slowly started to return. As of last night my FC did not drop from 23 but I can still see some algae on the bottom and around the return jet. Why does the algae keep returning is there something that I am doing wrong? I don't know if this is normal but every since I raised the shock level my TA sample will turn from green to yellow instead of red.

    My numbers are
    FC 23
    PH 7.4
    CYA 80
    TA about 120 sample turns yellow instead of red
    Intex 16' X 32' X 52" 14,364 galllon AGP, 16" sand filter & SWG, Pool Rover & Sunrise Journey SPA 320 gallons, TechniChlor 110 SWG

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    Mod Squad JohnT's Avatar
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    You shouldn't have algae growing with a FC of 11. Are you sure it isn't tree pollen or some other kind of dust? The fact that it's around the returns doesn't say algae to me, but makes me think filter problems.

    The TA test works differently in the presence of high chlorine.
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    AnnaK's Avatar
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    My wild guess is that the 2 drops of chlorine neutralizer that go into the 25 ml sample at the beginning of the TA test aren't enough for a FC = 23. You could try it with a dilution: mix 1/2 pool water with 1/2 distilled water and test 25 ml of that for TA, then multiply the result by 2.

    As to the returning algae, I would brush the bottom and keep the pump running. We sometimes have algae on the return jet. I use a small nail brush and an old toothbrush to remove that. In high summer it's not unusual for there to be a spot or two of algae growing in the shaded parts of the pool. We've been able to control those with brushing and raising the FC from 3 to 5 (at CYA = 30)

    AnnaK
    AnnaK

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    Quote Originally Posted by JohnT
    You shouldn't have algae growing with a FC of 11. Are you sure it isn't tree pollen or some other kind of dust? The fact that it's around the returns doesn't say algae to me, but makes me think filter problems.

    The TA test works differently in the presence of high chlorine.
    Hey John,

    Thanks for the help. It appears to be algae it is also under the stairs. I will try to post some pictures tonight when I get home.

    Eddie
    Intex 16' X 32' X 52" 14,364 galllon AGP, 16" sand filter & SWG, Pool Rover & Sunrise Journey SPA 320 gallons, TechniChlor 110 SWG

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    Quote Originally Posted by AnnaK
    My wild guess is that the 2 drops of chlorine neutralizer that go into the 25 ml sample at the beginning of the TA test aren't enough for a FC = 23. You could try it with a dilution: mix 1/2 pool water with 1/2 distilled water and test 25 ml of that for TA, then multiply the result by 2.

    As to the returning algae, I would brush the bottom and keep the pump running. We sometimes have algae on the return jet. I use a small nail brush and an old toothbrush to remove that. In high summer it's not unusual for there to be a spot or two of algae growing in the shaded parts of the pool. We've been able to control those with brushing and raising the FC from 3 to 5 (at CYA = 30)

    AnnaK
    Hi Annak,

    Thanks for your help. We have been running our pump 24/7 since the first shock treatment. I will try the dilution method and also an old toothbrush tonight but last night I tried rubbing my finger across it and some gave off but some would not.

    Eddie
    Intex 16' X 32' X 52" 14,364 galllon AGP, 16" sand filter & SWG, Pool Rover & Sunrise Journey SPA 320 gallons, TechniChlor 110 SWG

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    AnnaK's Avatar
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    What kind of stairs do you have? Algae under wedding cake steps is pretty common because water circulation is limited there. Some ways to control it are:

    * When you backfill with water, put a nozzle on the hose and hang it behind the steps so a sharp stream of water enters there;

    * When you add bleach, pour some of it directly behind the steps (between steps and pool wall);

    * You can drill some additional holes into the sides of the steps. We added three 2" holes on each side of ours to allow for better circulation.

    * When you brush the pool you can push water against the steps. If you've put more holes in them you add to the circulation.

    Take a look at the Pool Issues link in my signature for photos.

    AnnaK
    AnnaK

    12,500 gal AGP, Hayward sand filter, Pentair 2-speed pump, timer.
    Please visit our Pool Issues pages for information about step weights, managing the solar cover, and PoolSkim.

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    Eddie,

    Just to confirm what John and Lisa have already said......in the presence of high chlorine, the ALK test will frequently go to yellow instead of red. The test results are still perfectly valid, as the directions on the TF-100 indicate.
    Dave S.
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    JasonLion's Avatar
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    Pollen can look very much like algae in some situations.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Here is a picture of the algae on the return jet and one of the pool bottom. I tried brushing the algae from the return jet and some did come off but even if I scraped with my fingernail it still would not remove all of it. Also my numbers that I got tonight are the same as they were this morning.

    Thanks,
    Eddie
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    Intex 16' X 32' X 52" 14,364 galllon AGP, 16" sand filter & SWG, Pool Rover & Sunrise Journey SPA 320 gallons, TechniChlor 110 SWG

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    AnnaK's Avatar
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    Eddie, that does look like algae alright.

    What kind of test kit do you use? Is it possible that the test results are incorrect?


    AnnaK
    AnnaK

    12,500 gal AGP, Hayward sand filter, Pentair 2-speed pump, timer.
    Please visit our Pool Issues pages for information about step weights, managing the solar cover, and PoolSkim.

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    I think that brushing will help solve this problem. When you raise your free Cl2 to shock levels and adding the brushing you brake up the Bio film that can protect the algae.
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    I am using a Taylor K-2006 test kit. I just went out and tested the water again and I am still coming up with the same numbers. I also have a Leslie pool store service kit and it is reading the same.

    Eddie
    Intex 16' X 32' X 52" 14,364 galllon AGP, 16" sand filter & SWG, Pool Rover & Sunrise Journey SPA 320 gallons, TechniChlor 110 SWG

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    AnnaK's Avatar
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    IMO, we need to keep brushing and we need to keep the FC at shock level for a CYA = 80 until the test for CC = 0. You hadn't posted the CC reading previously. Per the Chlorine/CYA chart in the Stickies, shock level is 40% of CYA, or 32 ppm of FC in your system. It looks like running it at 23 ppm FC isn't enough for the amount of CYA in the water.

    AnnaK
    AnnaK

    12,500 gal AGP, Hayward sand filter, Pentair 2-speed pump, timer.
    Please visit our Pool Issues pages for information about step weights, managing the solar cover, and PoolSkim.

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    JasonLion's Avatar
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    Brushing everything will help. It takes time for chlorine to break down bio films. Brushing helps the chlorine get in and breaks them down much more quickly.

    Quote Originally Posted by AnnaK
    Per the Chlorine/CYA chart in the Stickies, shock level is 40% of CYA, or 32 ppm of FC in your system. It looks like running it at 23 ppm FC isn't enough for the amount of CYA in the water.
    At higher CYA levels the straight 40% rule isn't exactly right. Raising FC to 32 will speed the process up, but 21 is sufficient.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    I have been brushing the pool the best I can every night. Last night I raised my FC level to 30 and this morning I woke up to a VERY dishearten situation. We now have about a two inch tear in the liner. Could this tear have been caused from raising the FC level? My numbers this morning were:

    FC 30
    CC .5

    But of course now all my numbers are going to change due to the loss of water. Since I had to go to work today my brother is going to come by and see if he can patch the liner for me. If he can patch the liner should I do anything different before or during refilling of the pool? If the liner can not be patch my son is going to be very upset because we will be getting rid of the pool. These on going algae problem has just been to much of a hassle to justify dumping anymore big money into the pool.

    Thanks,
    Eddie
    Intex 16' X 32' X 52" 14,364 galllon AGP, 16" sand filter & SWG, Pool Rover & Sunrise Journey SPA 320 gallons, TechniChlor 110 SWG

  16. Back To Top    #16
    JasonLion's Avatar
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    I am sorry you are having so many problems.

    It is very unlikely that the FC level had anything to do with the liner tearing.
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    AnnaK's Avatar
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    Oh no! I'm so sorry to hear of this new problem. No wonder you're frustrated. How old is the liner?

    Jason, thanks for clarifying the 'CYA rule'.
    AnnaK

    12,500 gal AGP, Hayward sand filter, Pentair 2-speed pump, timer.
    Please visit our Pool Issues pages for information about step weights, managing the solar cover, and PoolSkim.

  18. Back To Top    #18

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    My brother just called me and said that he got the leak stopped. The liner and pool is only four years old. What is the average life span of a liner? Tonight when I get home I will start the refill process. How long after the pool is full should I wait until I take a new set of numbers? I have been fighting this algae problem for about two years and needles to say I gave the pool stores LOTS of money. I finally said there is got to be a better way so that is when I found this site. I am getting really tried of fighting and looking at that green swap. Please help me get this back to the pool that we used to love. I have been using Jason's Pool Calculator to determine the amount of bleach to add according to my FC and CYA level. Should I continue to use that calculator or should I just try to keep my FC level at a certain amount for a certain time period. I have also been following the sticky "Turning Your Green Swamp Back into a Sparking Oasis" that was posted by Jason. Thanks to everyone for all the help they have provided so far and any help turning this pool around will be greatly appreciated.

    Thanks again,
    Eddie
    Intex 16' X 32' X 52" 14,364 galllon AGP, 16" sand filter & SWG, Pool Rover & Sunrise Journey SPA 320 gallons, TechniChlor 110 SWG

  19. Back To Top    #19
    JasonLion's Avatar
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    Ideally, the water should circulate with the pump running for an hour before testing.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    AnnaK's Avatar
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    My liner has a 15 year prorated warranty, whatever that means, with a free replacement the first 3 years. That makes me think the average lifespan is 4 - 5 years. It would depend a whole lot on use, exposure to sun and chemicals, care and maintenance, I'm thinking.

    I understand your frustration with the ongoing algae battle but you CAN win this. Many of us have been in your place and we've all succeeded. The silver lining <GROAN> of the vinyl tear and loss of water is that your CYA will drop some when you've refilled. Let's take a look at the new numbers after the fresh water has circulated for at least an hour.
    AnnaK

    12,500 gal AGP, Hayward sand filter, Pentair 2-speed pump, timer.
    Please visit our Pool Issues pages for information about step weights, managing the solar cover, and PoolSkim.

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