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Thread: Algae creeping back?...but FC is good!

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    Algae creeping back?...but FC is good!

    Brief history: last week I had to SLAM my saltwater pool. One day I noticed sediment on the bottom, and thought it was dirt and pollen. The stuff would brush up in a yellowish green puff, and disappear. The next day the pool was cloudy and became increasingly yellow/green as the day went on. I raised FC to 24 and held it there for during the day/evening, and it passed the OCLT that night. In the morning I vacuumed the dead algae, and the water looked perfect! I let FC slowly drift down for the next couple of days, then turned on the SWG and held FC at 8. FC has been in the range of 6 to 8 every time I've checked with my DPD test. CYA is 55. Water has been beautiful for several days.

    This morning, the sediment is back. Not much, but enough to notice. It behaves the same as it did when I noticed it last week - brushes around in a yellow/greenish puff and disappears. I've read about mustard algae but I also know it's not common. I want to know what is causing this stuff to come back, after a successful SLAM and maintaining proper FC. Do I need to go ahead and SLAM again now to stop it before it takes hold again? Or could it just be dirt?

    FC 8
    CC 0
    pH 7.5
    CYA 50 - 55 (planning to raise to 60 but want wait until after a SLAM if it's required again)
    TA 90
    CH 100
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    Mod Squad kimkats's Avatar
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    Re: Algae creeping back?...but FC is good!

    I would do the SLAM again for a little longer to make sure the algae is gone. Did you backwash and rinse your filter? Use a toothbrush to really clean all around the returns and skimmer box. Do you have a light? If so take it out and see what is behind it.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Algae creeping back?...but FC is good!

    Quote Originally Posted by kimkats View Post
    Do you have a light? If so take it out and see what is behind it.

    Kim
    Just tried to remove the light, but I can't get the screw out...
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    Mod Squad pooldv's Avatar
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    Re: Algae creeping back?...but FC is good!

    Maybe shoot a garden hose around the edges to blow any debris out or put some bleach in a spray bottle and spray it in around the edge.
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    Re: Algae creeping back?...but FC is good!

    Quote Originally Posted by pooldv View Post
    Maybe shoot a garden hose around the edges to blow any debris out or put some bleach in a spray bottle and spray it in around the edge.
    Thanks! I'll try this. I couldn't see any gunk near the light area, but I would like to check behind it.

    If I pass the OCLT tonight and have 0 CC, is it safe to assume this is not algae returning? Or do you suggest going ahead with a SLAM anyway?
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    Mod Squad kimkats's Avatar
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    Re: Algae creeping back?...but FC is good!

    Did you mess up the head of the screw trying? You can also use needle nose pliers to carefully help the screw driver to get it out.

    I would keep your FC in the upper limits for a couple/few days just to make sure you are done.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Algae creeping back?...but FC is good!

    Quote Originally Posted by kimkats View Post

    I would keep your FC in the upper limits for a couple/few days just to make sure you are done.

    Kim
    Thanks Kim! When you say upper limits, do you mean upper limit of the target FC (my target is 6-8) or the upper limit of the shock level FC (which would be 20 in my case)?

    Ok for the kids to swim at shock level?
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    Re: Algae creeping back?...but FC is good!

    I believe Kim meant high end of target or even a tad above that, but not all the way to shock. Generally speaking, as long as PH is in range, it is safe to swim up to shock level, provided you passed the 3 slam criteria to ensure nothing is growing in there.

    I totally agree with Kim's advice to check behind everything, including light. For me, the culprit was behind the return eye. Picture here.
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    Re: Algae creeping back?...but FC is good!

    Quote Originally Posted by BattleOfYakima View Post
    I believe Kim meant high end of target or even a tad above that, but not all the way to shock. Generally speaking, as long as PH is in range, it is safe to swim up to shock level, provided you passed the 3 slam criteria to ensure nothing is growing in there.

    I totally agree with Kim's advice to check behind everything, including light. For me, the culprit was behind the return eye. Picture here.
    What he said ^^ LOL Tom and I seem to be able to know what the other is saying or will say.

    Kim (thanks Tom!)
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    Re: Algae creeping back?...but FC is good!

    Good morning! I bumped up FC to 10 yesterday evening. Ran the OCLT this morning and only lost .5ppm. CC was between 0 and .5 (there was a slight pink tinge to the water but practically clear). BUT the shallow end was covered in splotchy gunk. It's not on the sides of the pool - mainly bottom of the shallow end and along creases. It brushes up into a cloud and "disappears." See pictures...

    I just raised FC to shock level to start a SLAM. I plan to try to remove the lights today to check behind them. I didn't want to risk damaging the screw heads yesterday, so I'm going to recruit my handy husband to help

    Here's where I'm scratching my head:

    1. If FC levels have been higher than target since my successful (?) SLAM last week, should algae be able to return? (Unless of course there is a bunch of it hiding behind the lights). How can I keep it from returning again after this SLAM?
    2. I've read about mustard algae, not sure if this fits the bill or not. My pool doesn't really have a shady side so it's hard to tell. Does anyone think a mustard shock is necessary?
    3. Can someone explain the difference between living algae and algae dust or dead algae? I've been obsessively reading the forums and it seems everyone thinks it's just dirt or dust, then turns out to be an algae bloom. Mine doesn't appear to be growing on any surfaces, just sort of hanging around in dusty splotches.

    IMG_9895.JPGIMG_9897.JPG
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    Re: Algae creeping back?...but FC is good!

    I would do a "to waste" vacuum to get it up and out. If it POOFS when you touch it it is dead algae. If it is dirt will would go not go POOF.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Algae creeping back?...but FC is good!

    Quote Originally Posted by kimkats View Post
    I would do a "to waste" vacuum to get it up and out. If it POOFS when you touch it it is dead algae. If it is dirt will would go not go POOF.

    Kim
    Will do. What does living algae do when you brush it? (i.e. am I dealing with growing algae or dead algae?) Still trying to figure out what I did wrong - the water was clear for a week post-SLAM and then the "poofy dust" came back.

    Also should note that the dust re-settled within an hour after brushing.
    saltwater generator - Hayward turbo cell
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    25,000 gallon vinyl pool (20x40 rectangular)
    Polaris 280
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    Re: Algae creeping back?...but FC is good!

    live algae=green POOF.............dead algae-gray POOF

    Dirt really does not POOF, it scatters. SO hard to tell, it is something that has to be seen.

    There is something that is hiding algae-ladder, light, skimmer box or door, return eye, etc.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Algae creeping back?...but FC is good!

    Collect some of this debris and rub it on a white sheet of paper and let it dry. If you see greenish streaks it is algae. Could it be pollen? Is anything blooming in your area? Have you see "dust" on outside furniture or cars?
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    Re: Algae creeping back?...but FC is good!

    I was able to get one of the lights out. Inside the cavity there was a bunch of dirt...I vacuumed this out. The light itself had some green algae around the seal area. It's soaking in bleach.

    The screw for the other light is completely stripped. I'm going to have my husband take a look.

    I've done my best to vacuum the *hopefully* dead algae to waste. I'm keeping the pool at shock level all day.
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    Re: Algae creeping back?...but FC is good!

    Congratulations on getting out one of the lights! I'm so proud of you! Other tactics you and/or husband can try is a larger screw driver, a different shape screwdriver head that can get a bite on it, trying the correct screwdriver but placing a rubber band between the screwdriver and the screwhead (works a surprising amount of the time), or borrowing/buying an extractor like this sub $5 shipped one. Other options include drilling out the screw manually, which seems way to hard, or hammering another screwdriver into it, which also seems rough to do potential of metal shavings being developed.
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    Re: Algae creeping back?...but FC is good!

    Quote Originally Posted by zea3 View Post
    Collect some of this debris and rub it on a white sheet of paper and let it dry. If you see greenish streaks it is algae. Could it be pollen? Is anything blooming in your area? Have you see "dust" on outside furniture or cars?
    I would do as zea says also. Use a turkey baster to get some of the stuff.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Algae creeping back?...but FC is good!

    Thanks all! We tried removing the second light last night with no luck. Going to buy an extractor this morning.

    Passed OCLT last night. FC is 20. 0 CC so I assume that is a good sign. Water looks clear except for the settled stuff, which is hard to vacuum because a lot of it just poofs away!

    Does anyone think I need a mustard shock? I doubt I have mustard algae...But I'm at a loss because the pool looked clean and beautiful just like this after I did the SLAM last week, and then all the "dust" came back a week later. Like I mentioned in my first post, the FC level has been above target since the SLAM. It's also worth mentioning that the dust started on the floor and slanted walls, and would poof into a yellow/green cloud when brushed. After FC was at shock level all night, there are now sandy brownish-gray patches on the bottom, and no dust on the slanted walls/floor. The water is otherwise clear. This is exactly what happened last week after my SLAM.

    As for pollen/dirt, there's not much blooming other than the flowers in the yard and no pollen settling elsewhere. We have had some rain though.

    I will dive in and collect some of the sandy brown/gray stuff that settled in splotches last night and see what it looks like on paper (thanks for that tip!)
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    Re: Algae creeping back?...but FC is good!

    My guess: since you passed the OCLT, as long as you are only losing 2-4 FC per day now, you killed all the algae except potentially no circulation hiding spot stuff. I suggest posting your most recent, if avail, or next 4 test results to give the experts an idea about FC consumption to determine if you are still fighting anything or not.

    im not sure what is common in Alabama, but in Washington, 24 hours after a vac the winds have already delivered enough dirt to make me want to vac again. I didn't know this was even happening before I could see the bottom lol. In Florida I don't get near as much wind dirt, but when my back yard is mowed sloppily of when it is windy, then the floor will get dirty immediately. In Florida rain also washed deck dirt in the pool. Any of these seem like possible explanations for your recurring dirt, if that's what paper test indicated.
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    Re: Algae creeping back?...but FC is good!

    Thanks. The reason I'm doubtful it's just dirt is because it started off as yellow/green dusty stuff all over the floor and slanted walls of the pool. Then after raising FC to shock level, it all fell to the bottom in sandy/dusty patches. Seems like dirt wouldn't respond to a shock. Am I thinking correctly here?

    Still can't get the screw out to reveal what's behind that light!! The screw extractor needs to be used with a drill...but obviously that can't be done underwater, right? We tried using a socket but couldn't get enough force. Going to go back to the store and get an extractor in a slightly bigger size. If this doesn't work, I don't know what will...

    Last set of test results (taken this afternoon):

    FC 13 (SWG is also running at 40%)
    CC 0
    CYA 50
    TA 90
    pH between 7.5 - 7.8
    CH 90

    The water looks great today. I am just very worried this will repeat itself and the dusty stuff will come back again, because the pool responded just like this when I did the SLAM last week.
    saltwater generator - Hayward turbo cell
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