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Thread: Why do I have Algae? my #'s look good

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    Join Date
    Jun 2015
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    Freehold, NJ
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    Question Why do I have Algae? my #'s look good

    Hey All,

    I needed your advice on why I could have an algae problem as I am stumped. Just a background, I opened my pool and had an algae issue and completed the SLAM process with meeting all 3 of the criteria. Since then, I have had no issues and have kept my FC above the target chlorine level on the chart. For the last couple of days, I have seen a steadily increasing green film at the bottom of the pool. On the 2nd day of seeing this, these were my #'s:

    FC: 9.0
    CC 0.5
    pH 7.5
    TA 100
    CH 125
    CYA 50

    Even with my FC levels, the algae is in full bloom. I guess I have another SLAM coming my way, however just want to know what could have gone wrong so it doesn't happen again. Also, there has been heavy downpours here recently, could that have played a role?

    Thanks
    20'X40' Inground Vinyl Pool
    3ft to 8 Ft deep
    Filter: Hayward Pro Series High Rate Sand Filter
    Pump: Hayward 1.5 HP Super Pump
    Pool Cleaner: Dolphin Nautilus Plus

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    needsajet's Avatar
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    Re: Why do I have Algae? my #'s look good

    Your water chemistry looks good. Most common things other than inadequate FC would be lack of weekly brushing or missing some of the pool surfaces when brushing and/or inadequate circulation in some areas of the pool. This might allow algae to get started, and then of course it has a base to continue growing from. Sorry to hear you're seeing algae and yes, that's one of the indicators that you need to SLAM.

    I like to do an OCLT now and then just so I know there isn't too much algae in the water still at the invisible stage. Higher average daily consumption of FC can be an indicator, but that gets muddied by the varying weather and bather load.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Freehold, NJ
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    Re: Why do I have Algae? my #'s look good

    I guess to be completely honest, I hadn't brushed the walls for a couple of weeks, however I did run my dolphin cleaner several times. i thought that would suffice.
    20'X40' Inground Vinyl Pool
    3ft to 8 Ft deep
    Filter: Hayward Pro Series High Rate Sand Filter
    Pump: Hayward 1.5 HP Super Pump
    Pool Cleaner: Dolphin Nautilus Plus

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    needsajet's Avatar
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    Re: Why do I have Algae? my #'s look good

    Yep, the dolphin does brushing. Maybe it's missing areas and a touch-up with the brush if it's missing somewhere might help?

    The other possibility is a SLAM that wasn't quite finished. Your FC levels look fine so something is contributing
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Mod Squad kimkats's Avatar
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    Re: Why do I have Algae? my #'s look good

    Let me tell you are little story of the husband that did not do his ONLY job with the pool-brush the sides of the pool. I was in the pool one day and noticed there was a faint green tint to the side. When I brushed it with my hand it came off in a little cloud. Hummmmmmmm "Honey? When did you last brush the pool?" "ummmmmm A couple of days? It looked fine so..." I had him come over and watch me make the little green cloud again. You have never seen a person get in a pool so fast with the brush in their hand! LOL

    My numbers were spot on as I had just tested them before I got in the pool. My pool cleaner (bottom only) Wanda does the bottom very well but the sides do need to be brushed at least 3 times a week.

    Do you have a light? If so take it out and look behind it.

    Have you taken the steps out? If not possible have you brushed them all around? How about a tooth brush for you returns and skimmer face?

    Let us know what you find.

    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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    Join Date
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    Freehold, NJ
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    Re: Why do I have Algae? my #'s look good

    I don't have any lights in the pool...
    I do have two stairs and 5 returns and 1 vacuum port. I never specifically cleaned around them, however i do brush near them every now and then. I assumed my dolphin was taking care of the brushing and felt if I kept my FC levels high enough, I would be ok.

    These are todays #'s and I just started the SLAM, hopefully it takes care of the problem.

    FC: 8
    Ph 7.5
    TA 100
    CH 125
    CYA between 40/50 (probably closer to 40)
    CC 0.5 (turned very faintly pink if at all )
    20'X40' Inground Vinyl Pool
    3ft to 8 Ft deep
    Filter: Hayward Pro Series High Rate Sand Filter
    Pump: Hayward 1.5 HP Super Pump
    Pool Cleaner: Dolphin Nautilus Plus

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    needsajet's Avatar
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    Re: Why do I have Algae? my #'s look good

    When CYA is between two lines, we round up to the higher number, so we'd call that 50 ppm CYA and SLAM at 20 ppm FC.

    Good luck annihilating the algae. The M in SLAM is maintain, maintain, maintain, which is also the best way to speed it up.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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