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Thread: Pool went green after a week of rain

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    Pool went green after a week of rain

    Background:

    Bought house 2 years ago. Blindly chlorinated with pucks and powdered shock the first year and used the test strips (I know, I know).

    Massive rain storm in June of 2012, turned the pool green. Switched to using liquid chlorine at that time on advice of local pool store. Still didn't switch to decent testing supplies. Dumped about half a jug of 10.5% once a week when it was hot and cleaned filter every week or two. When it was cold I hardly had to do anything.

    Fast forward to May 2013. Rained for a week solid, pool turned green again, water up over the top of the skimmer. Finally ordered TF-100 and am awaiting its arrival, so I have two testing method, these crappy 6 way test strips with expiration of 5/2014, and a generic 5 way drops in tubes based test kit. Dumped a full jug of chlorine in the pool brushed, cleaned filter, etc. Pool turned greener. Tested water with strips. Total chlorine zero, free chlorine like 10ppm+. What the huh? Tested with the drops, which only go to 5ppm. Test says check the free level immediately after mixing, and then wait 2 or 3 minutes and check color again for combined chlorine. Both say 5+. I brush, clean filter every day, run pump 24x7 for several days, pool is still bright green. Filter is not getting the dark green stuff like I am expecting. Went to pool store yesterday on the way home and picked up 4 jugs of 10.5%, dumped one in last night pump running filter 24x7. No change this morning. I dump in another 2.5 gallon jug, clean filter, which is still not getting very visibly dirty.

    Right now, the filter pressure is 6psi which is as low as it goes. Based on the test strips, which I absolutely hate, because they don't seem accurate and I have a hard time distinguishing between the colors, my readings are approximately:

    Total hardness: 250ppm
    Total chlorine: 10ppm+
    Free chlorine: 20ppm+
    pH: Cannot tell from the strips. The colors from 7.2 - 8.4 on the sticker look too similar to me
    Total alkalinity: ~120ppm
    Stabilizer: Can't really tell, color doesn't look like the bottle. I think somewhere 50 - 100?

    From the drops, the chlorine is way over 5ppm, which is as high as the chart goes. The top of the chart is deep yellow, the water is almost red.
    The pH from the drops appears to be up over 8.2 which is as high as the chart goes. Another test on there is acid demand, which indicates I need 1.5 - 2 gallons of acid to get down to 7.4. The only other test I have right now is the total alkalinity test from the drops, which seems about 200ppm.

    The water smells very strong of chlorine right now, so I really think I am good there for the time being, but I don't understand why the green is going nowhere.

    On another note, prior to the rainy week, the pH registered really, really high, and according to the acid demand chart, I needed 2 gallons of acid, so I put that in and it stabilized around 7.4 for several days before the rain. How in the world does the pH keep skyrocketing like this? Or is there something else going on that makes the pH reading wrong?
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Richard320's Avatar
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    Re: Pool went green after a week of rain

    High TA and the aeration from the rain are probably what's driving the pH up.

    Is the pool have clear green or cloudy green water? Can you see the bottom? Have you used any copper-based algaecides?

    You might also have had the CYA break down into ammonia from that elusive bacteria, which will consume huge amounts of chlorine.

    But it's all speculation right now until you have accurate test results.

    Can I bookmark this thread and use it as an example of why we push so hard for proper test kits here?
    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: Pool went green after a week of rain

    It's cloudy now I guess. I can see the bottom just barely at the shallow end, but at the deep end, not a chance. Anything else I can do while I wait for the kit to arrive?
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    msgtdan's Avatar
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    Re: Pool went green after a week of rain

    When you have a strong chlorine smell that means the chlorine is killing something. When everything is balanced you won't hardly notice a smell at all. You're going to have to go through the shock process, but until you get a good test kit it'll just be guess work.
    Dan D
    Used 2003 Aqua Leader 27'x52", 17,800 w/10" hopper, SwimPro SW256T 250# sand filter, Hayward PowerFlo LX pump 1hp impellor, Emerson 1 1/2 hp motor, setup Aug 2012 Summer 2011 used Summer Escapes Ring pool 14' x 42", Intex 1600gph sand filter, HTH 6 way test kitTF-100 w/stirrer, Well water @ FC=0, PH=7.2, TA=290, CH=320

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    Re: Pool went green after a week of rain

    24 hours later with pump running constantly, PSI climbed up to 6.5 or maybe 7. Chlorine measurements I have available still show maximum free chlorine. Brushed the whole pool several times the best I can, but I can't see the brush head in the water deeper than about 4 feet. Pool is still green, doesn't look any better than yesterday. On the bright side, it doesn't look any worse, either.
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Re: Pool went green after a week of rain

    Or is there something else going on that makes the pH reading wrong?
    In the presence of high chlorine (10 ppm), the pH test is not valid....it is only accurate when the chlorine is lowered.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pool went green after a week of rain

    Kinda looks a little better today but still can't see the bottom. Free chlorine dropped some but is still above 10ppm best I can tell. The drop based test that only goes to 5 goes deep yellow, but not orange or red anymore. I'm tempted to dump in another jug of 10.5%, but I might wait until sundown. I cleaned the filter just for grins and so I felt like I was doing something, but it was only up to 7psi from 6. There was finally some green in the filter, along with a bunch of ants.
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Richard320's Avatar
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    Re: Pool went green after a week of rain

    Quote Originally Posted by aseigler
    Kinda looks a little better today but still can't see the bottom. Free chlorine dropped some but is still above 10ppm best I can tell. The drop based test that only goes to 5 goes deep yellow, but not orange or red anymore. I'm tempted to dump in another jug of 10.5%, but I might wait until sundown. I cleaned the filter just for grins and so I felt like I was doing something, but it was only up to 7psi from 6. There was finally some green in the filter, along with a bunch of ants.
    Why wait? Why give the algae a chance to regroup and reproduce? Hit it hard and constantly if you want a quick cleanup.
    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: Pool went green after a week of rain

    I guess, but wouldn't the chlorine just get burned up by the sun?
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Re: Pool went green after a week of rain

    Quote Originally Posted by aseigler
    I guess, but wouldn't the chlorine just get burned up by the sun?
    Some. But algae also grows in sunlight.
    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: Pool went green after a week of rain

    Makes sense. Dumped another jug in. It is amazing how fast it can go from clear to green, compared to how long it takes to get from green to clear.
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Re: Pool went green after a week of rain

    Got the TF-100 today. I am impressed at how much easier it is to read this test. The contrast in the colors is very helpful.

    I can barely see the bottom of the pool when I got home today. I skipped the mini kit since I was pretty sure there was much more than 5ppm of chlorine and didn't bother with pH or calcium either for the same reason. Numbers came out to:

    FC: 25
    CC: 0.5
    TA: 250
    CYA: 75

    For the FC test I stopped adding more drops of 871 as soon as it made a drastic change from pink to clear. I am puzzled at how the CYA test works...the stuff looks clear when it is going in and from the side, but sure enough, that black dot disappeared. I had no idea that having that much CYA would effect the shock level. I haven't added any CYA in at least a year, maybe more, sometime before switching to the liquid chlorine. Based on the CYA chart I should be up closer to 30 ppm chlorine for shock and 8 - 9 normally...I'd been running like 2 - 4 based on the crappy tests I had before. No wonder I keep having so much trouble.

    Off to dump another half jug of 10.5% in now!
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Mod Squad jblizzle's Avatar
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    Re: Pool went green after a week of rain

    Sounds like you have a pretty good grasp on things now.

    Remember that the pH test reads too high when the FC > 10ppm, so good that you did not do it. Although we usually recommend adjusting the pH before you raise the FC to shock level.

    The CYA test is pretty sensitive to light, so make sure you follow the instructions. Here are more details:
    extended-test-kit-directions-t25081.html
    Jason, TFP Moderator
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    Re: Pool went green after a week of rain

    I'll run through the CYA test again tomorrow afternoon when it is bright out, and if it really is at 80, I'll have to start thinking about a partial refill.

    Thanks!
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Re: Pool went green after a week of rain

    Tested the CYA this afternoon in the super bright Florida sun, and I think I am way closer to 60 than I am 80. Also, I can see the bottom of the pool now. I found half a beef femur at the bottom of the deep end (wife gives them to the dogs). Pretty sure that was not helping the situation.
    23,000 gallons, in-ground, gunite
    Hayward C1200 cartridge filter system
    Pentair 1HP pump

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    Richard320's Avatar
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    Re: Pool went green after a week of rain

    Quote Originally Posted by aseigler
    Tested the CYA this afternoon in the super bright Florida sun, and I think I am way closer to 60 than I am 80. Also, I can see the bottom of the pool now. I found half a beef femur at the bottom of the deep end (wife gives them to the dogs). Pretty sure that was not helping the situation.
    Hmmm...aged to perfection!
    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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