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Thread: Algae but no FC loss on OCLT

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    Algae but no FC loss on OCLT

    Hi,
    Started following the TFP method about a month ago and things have been going pretty well. Discovered my CYA is 50 and I've been using the calculator to add the appropriate amount of bleach and keep the FC within recommended levels.

    My pool water is clear, but I get some greenish/brownish dust that's been gathering. I vacuum it up and it comes back. I raised to shock levels and vacuumed but it came back. Seemed like maybe Algae but here's the kicker:

    OCLT shows no loss! Tested FC at 6 and then was still at 6 the next morning.

    Maybe I don't actually have algea?

    My pool gets a lot of debris (pine needles, insects, etc). I run the pump 24/7 at around 25gpm based on an intelliflo calculator (boosted up to 35 gpm for 4 hours a day just for fun and to run the sweep)

    Any ideas?
    25k gal plaster pool, intelliflo vs, cva-24 pentair solar controller, very old polaris 390 sweep with a new pentair booster.

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    JesseSchmidt's Avatar
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    Re: Algae but no FC loss on OCLT

    It's probably just debris blown into the pool. If you had algae you would have loss overnight. Is it slimy to the touch? Or just "dusty", meaning when you brush it spreads into the water like dust into the air?
    26k Gal IG vinyl, Hayward Super 1HP, Hayward Pro Series S244T Sand Filter, TFTestkits TF-100 w/ Speedstir
    Links: TFPC for Beginners / ABCs of Pool Water Chemistry / GETTING STARTED / PoolMath / SLAM / TFTestkits / Chlorine/CYA Chart

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    Re: Algae but no FC loss on OCLT

    Quote Originally Posted by JesseSchmidt View Post
    It's probably just debris blown into the pool. If you had algae you would have loss overnight. Is it slimy to the touch? Or just "dusty", meaning when you brush it spreads into the water like dust into the air?
    Doesn't feel slimy - just dust.

    - - - Updated - - -

    IMG_2436.jpg
    25k gal plaster pool, intelliflo vs, cva-24 pentair solar controller, very old polaris 390 sweep with a new pentair booster.

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    Texas Splash's Avatar
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    Re: Algae but no FC loss on OCLT

    Hummm. I don't like the look of that plaster or steps around the bottom edges where it curves up. Can you posts a full set of water results from your TF-100 or Taylor K-2006?
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: Algae but no FC loss on OCLT

    Quote Originally Posted by Texas Splash View Post
    Hummm. I don't like the look of that plaster or steps around the bottom edges where it curves up. Can you posts a full set of water results from your TF-100 or Taylor K-2006?
    TA - 80
    Ph - 7.5
    CYA - 60
    FC - 5.5
    CC - 0.5
    TC - 6
    25k gal plaster pool, intelliflo vs, cva-24 pentair solar controller, very old polaris 390 sweep with a new pentair booster.

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    Texas Splash's Avatar
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    Re: Algae but no FC loss on OCLT

    Those numbers look pretty good. Is there any chance we could assume your FC dropped below the minimum of 5 based on your new CYA of 60? Maybe enough in this summer heat/sun to allow algae to kick-in? But it is odd that are passing OCLTs. Does that green brush-off easily? Can you grab or scratch any of it and smear it on some white paper to see if it's green? That stuff seems to be going up the side walls a bit in that photo right?

    Also, where does your water come from (well, city)?
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: Algae but no FC loss on OCLT

    Quote Originally Posted by Texas Splash View Post
    Those numbers look pretty good. Is there any chance we could assume your FC dropped below the minimum of 5 based on your new CYA of 60? Maybe enough in this summer heat/sun to allow algae to kick-in? But it is odd that are passing OCLTs. Does that green brush-off easily? Can you grab or scratch any of it and smear it on some white paper to see if it's green? That stuff seems to be going up the side walls a bit in that photo right?

    Also, where does your water come from (well, city)?
    Water comes from the city (EBMUD)

    The green brushes off very easily. If I touch it, it basically just disperses into dust. My pool sweep will kick it up from the bottom and leave a clean line in its wake. I will try the paper test later to see if it's green.

    It could be that I miffed the CYA test too and that my CYA is closer to 50 (the reagent was slightly above the label when I filled the CYA bottle in the TF-100)

    I went on vacation for 9 days and shocked right before I left and put 4 tabs in a floater as well (that would account for some change in CYA, but 10 ppm seems like a lot for 4 tabs, no?). I discovered today that while I was away the sweep was only getting to 1/4 of the pool.

    Another odd thing about my setup is my skimmer. The suction can be horrible sometimes and it looks like it wasn't sucking well while I was away. My skimmer has a float valve assembly which must have prevented the suction from working. Seems like an annoying feature. That would account for why the top of my pool had debris, but wouldn't really explain the algae, since the main drain should have been passing the water to the filter still, right?
    25k gal plaster pool, intelliflo vs, cva-24 pentair solar controller, very old polaris 390 sweep with a new pentair booster.

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    Texas Splash's Avatar
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    Re: Algae but no FC loss on OCLT

    The look of it and description of how it disperses definitely sounds like algae. Poor circulation could definitely contribute. Each tab could add anywhere from 6-9 ppm of CYA, so it's possible your CYA is higher than you thought, thus it would have required a higher FC while you were gone. We'll see if you come back with any more info.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: Algae but no FC loss on OCLT

    Couldn't get anything onto the paper. Interesting that each tab can raise CYA 6-9 - that is way more than I would have thought.

    Last night I raised FC to 8 and brushed the pool. Sides look clean this morning. Maybe I'll give it a vacuum today.
    25k gal plaster pool, intelliflo vs, cva-24 pentair solar controller, very old polaris 390 sweep with a new pentair booster.

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    Texas Splash's Avatar
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    Re: Algae but no FC loss on OCLT

    Sure. And in the future, whenever you are curious, just look at the near bottom of the Poolmath calculator and there's a row for "Effects of Adding Chemicals". It can tell you what to expect when you add certain products.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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