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Thread: a few green spots.

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    a few green spots.

    I could use a little help I am a little puzzled. I am a first time pool owner and have been using the BBB from the start. The issue I am having is I am starting to get green spots growing in a handful of places around the pool. The water looks beautiful nice and clear sparkling blue. Ran a set of tests last night with my Taylor k2006 kit below are the numbers.
    Temp: 82
    pH: 7.6
    TA: 110
    FC: 2.0 (before adding chlorine)
    CC: 0.0
    CYA: about 30 (I think! It is a bit hard to tell).
    I did run an OCLT the night before and my FC loss was only 0.2
    The other thing I have done is I have been trying to raise the CYA level a little to slow the loss of chlorine as the pool gets 100% sun from sun up to sundown. Anyone have any ideas why I am getting some green spots?

    My thought is that since I have been adjusting the CYA levels, I probably now have it above 30 (maybe 35 or so. Definitely not 40 as I can clearly see the dot at the 40 mark) so according to CYA/FC chart my chlorine would be low allowing the algae to start growing. The thing that is puzzling to me is that the water is so clear and perfect and the overnight test has shown no loss. Wouldn’t the water go cloudy or my overnight test show a bigger loss if there is clearly algae starting to form? Is that possible?

    The other question I have is about chlorinating. If my theory is correct and I am above 30 PPM CYA then I would need to chlorinate for 40 PPM CYA on the chart. So the min would be 3 with a target of 5. With that in mind under normal circumstances to me that would mean I would need to shoot for 8 PPM when adding chlorine if my normal usage is 3PPM per day. Does this sound correct? Is it safe to swim in with that much chlorine? How high a level of chlorine is safe without any negative effects?

    Thanks for the advise. I have gotten so much good information from this site
    14000 gal AG vinyl liner. 150lb Hayward sand filter 1hp 2 speed pump.

  2. Back To Top    #2
    Richard320's Avatar
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    Re: a few green spots.

    You have the targeting figured out exactly right. For 30 CYA, you can swim all the way up to 13 FC, so you're good there. For 40, it's 15 FC.

    Spots tell us you're not brushing enough.

    There are always going to be spots in the pool with poor circulation, and brushing eliminates them as well as scraping off the protective scab that algae grows.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: a few green spots.

    If my CYA is in the 30-40 range what would the normal rate of chlorine loss be due to the sun? From about 5:30 or 6 last night to 1 pm today I have already lost my normal 3ppm or 50% of my FC.
    14000 gal AG vinyl liner. 150lb Hayward sand filter 1hp 2 speed pump.

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    Richard320's Avatar
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    Re: a few green spots.

    Quote Originally Posted by Exit0
    If my CYA is in the 30-40 range what would the normal rate of chlorine loss be due to the sun? From about 5:30 or 6 last night to 1 pm today I have already lost my normal 3ppm or 50% of my FC.
    You lose a percentage of FC to sunlight, not a fixed PPM. So at a higher FC level, you lose more to sun; same percentage, but more PPM.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: a few green spots.

    So last night I chlorinated to 6ppm and when I tested tonight it was at 1.8 (below the minimum level for 30ppm CYA) for a loss of about 75% in one day. Would this be a reasonable loss? Tonight I added chlorine I shot for 8 but actually hit 8.8. Had to add the better part of a gallon of 12.5% chlorine to do it. If the same holds true tomorrow night I will be at 2.2ppm I will test in the morning to see if there was any loss over night. Just seems like it is awful lot of chlorine to be adding every day and end up below the minimum level. Is it possible my CYA is still not where I think it is?
    14000 gal AG vinyl liner. 150lb Hayward sand filter 1hp 2 speed pump.

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    Re: a few green spots.

    You probably have mustard algae. To get rid of it, you have to do the full shock process.

    pool-school/mustard_algae

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    Join Date
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    Re: a few green spots.

    It sounds like you are using the 25 mL sample for the chlorine test. You can use 10 mL to save reagent.


    John
    7 year old ~13,500 gal 24' AGP with 1.5 hp Proline pump, 150 sqft Pleatco cartridge, filled with well water with pH of about 4.5.
    Wanda the Whale pool vacuum, home made heater, Taylor K-2006
    Cloudy Pool? 1) Order test kit. 2) Follow SLAM
    New to TFPC? Read Pool School a few times, then post questions. PoolMath will help with chemical additions.

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    techguy's Avatar
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    Re: a few green spots.

    I have been losing about the same percentage of CL in my pool. I know it's because I have a CYA of 30, it's been over 110f today and its very sunny. I plan on bringing up my CYA this week.
    -- Guy --
    10K gallons in 21' Round 52 inch wall Aqualeader AG, Hayward Power Flow LX 1.5 HP pump motor, Hayward Perflex EC50AC DE filter w/Cellulose, Wide mouth skimmer, 2013 new Diver Dan (craigslist) to replace the faded old Hayward AquaBug. TF-100

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    Re: a few green spots.

    My OCLT is complete. From 8pm last night to 7am this morning my pool consumed 1ppm. Sounds like I will need to start the shock process.
    14000 gal AG vinyl liner. 150lb Hayward sand filter 1hp 2 speed pump.

  10. Back To Top    #10

    Re: a few green spots.

    The sun is off the pool and I started the shock process and brushed the pool thoroughly. The good news is my chlorine consumption slowed some today. I was reading in the pool school section on chlorination. In there it says that it is normal to have to raise FC 2-3 PPM each day. after the shock process is complete I will be reasonably sure there will be no organics or any other abnormal chlorine load. if this is the case and I am still using a large amount of chlorine, the only other reason for the loss would be from the sun? Is that true? If so I was thinking that I might have to bump my CYA to 40 to 50 range. Would that be the correct thing to do? Will that really slow the loss that much? Would like to get the advise of the experts before I add more CYA.
    14000 gal AG vinyl liner. 150lb Hayward sand filter 1hp 2 speed pump.

  11. Back To Top    #11
    Richard320's Avatar
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    Re: a few green spots.

    Quote Originally Posted by Exit0
    The sun is off the pool and I started the shock process and brushed the pool thoroughly. The good news is my chlorine consumption slowed some today. I was reading in the pool school section on chlorination. In there it says that it is normal to have to raise FC 2-3 PPM each day. after the shock process is complete I will be reasonably sure there will be no organics or any other abnormal chlorine load. if this is the case and I am still using a large amount of chlorine, the only other reason for the loss would be from the sun? Is that true? If so I was thinking that I might have to bump my CYA to 40 to 50 range. Would that be the correct thing to do? Will that really slow the loss that much? Would like to get the advise of the experts before I add more CYA.
    You are correct, but don't add the extra CYA until you've passed all three parts of the shock process final exam. If you do, you will also raise the the shock level and need to buy more bleach.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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