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Thread: What is this?

  1. Back To Top    #1

    What is this?

    This is the second year I've had this. I'm not sure what it is. Pool has been fine since I opened in the end of May. Last Saturday I was going to let the nephews come swimming and when I pulled the cover back it was all over the deep end and slant. I had this last year. I would SLAM and then once all three criteria passed I would hold it at mustard levels for 24hrs. It would still come back. I have no OCL and I have been keeping my FC at 3.5 to 4 since I opened.

    FC - 3.5
    Ph - 7.6
    CYA - 30
    CC .5
    Attached Images Attached Images
    24000 Gallons
    Cristal-Flo Hi-Rate Sand Filter
    IG - Vinyl
    3/4 HP Pump, and 44 Flow Rate
    Older than 10 years.

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
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    Re: What is this?

    Sure looks like green algae to me.

    Note that if you do think you have mustard algae, you may need to keep the FC above 4.5ppm for a CYA of 30ppm according to Chlorine/CYA Chart

    Maybe you are not getting good circulation in the deeper end?
    Do you have a floor drain that is pulling water?
    Are the jets pointed down some?
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  3. Back To Top    #3
    JoyfulNoise's Avatar
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    Re: What is this?

    In that 2nd picture, am I seeing a vinyl seam running across the image?

    Does that side of the pool get lots of shade?


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  4. Back To Top    #4

    Re: What is this?

    @ Jblizzle - Last year was when I shocked @ mustard levels. The 3.5 and 4 FC reference was just stating what I have been keeping it at since I opened. Also, now that you mention it. I don't think I ever opened the floor drain after vacuuming about 3 weeks ago.

    @Joyfulnoise - Yes that is a seam and pretty much the entire pool except for some of the shallow end is in the shade most the day.
    24000 Gallons
    Cristal-Flo Hi-Rate Sand Filter
    IG - Vinyl
    3/4 HP Pump, and 44 Flow Rate
    Older than 10 years.

  5. Back To Top    #5

    Re: What is this?

    Are you thinking it is green algae and not mustard? It seems to be in only the areas where it is shady most the day. It's not on the walls just on the slopes and in the rounded area where the wall meets the floor.
    24000 Gallons
    Cristal-Flo Hi-Rate Sand Filter
    IG - Vinyl
    3/4 HP Pump, and 44 Flow Rate
    Older than 10 years.

  6. Back To Top    #6
    JoyfulNoise's Avatar
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    May 2015
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    What is this?

    Quote Originally Posted by epxroot View Post
    Are you thinking it is green algae and not mustard? It seems to be in only the areas where it is shady most the day. It's not on the walls just on the slopes and in the rounded area where the wall meets the floor.
    I always find it hard to determine the algae type from a picture. I think there's a smear test you can do where you try to rub some off with your finger and then onto a bright white card to see what color the algae is.

    Either way it definitely looks like algae to me and I have read that algae can get into vinyl seams and be very well protected from chlorine exposure. I have no idea how to get at it other than sustain shock levels of chlorine and vigorous brushing.

    Since your pool seems to be very reactive to algae growth and shaded a lot, you may need to consider secondary sanitation methods such as adding 50ppm borates to the water or using weekly maintenance doses of polyquat-60 algaecide. You should also consider keeping your target FC at a higher limit to ensure a larger FC/CYA ratio which is effectively a higher kill dose of hypochlorous acid.

    Finally, if secondary sanitation methods don't yield cleaner water, you may need to test for algae nutrients in the form of nitrates and phosphates. Some folks have used phosphate removers to lower phosphates below 100ppb which then makes the water less favorable to algae growth should your FC accidentally drop below an appropriate kill level. Nitrates can only be removed via water replacement. These methods of nutrient removal only help if the FC/CYA ratio is consistently observed since that is what actually kills algae. Making the environment starved of nutrients only acts as insurance should the FC/CYA ratio accidentally drop below proper sanitation levels.

    I also noticed in your signature that you don't mention your chlorination method? Do you manually dose with bleach everyday? Automation of sanitizer dosing can help a lot too. You might consider either a salt water chlorine generator or a Stenner pump for bleach dosing. In your situation, keeping your daily FC swings to a minimum would help a lot too.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  7. Back To Top    #7

    Join Date
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    Re: What is this?

    My neighobor's pool had algae "under" a seam. He used a hand held suction cup to keep him under water (you could use a brand new plunger or a weight belt) and then scrubbed under the seam with a toothbrush. It was a small section where the seam wasn't fully attached.

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