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Thread: Green water, confused readings

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    Join Date
    Jul 2011
    Location
    Northern MN
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    Green water, confused readings

    Hi all,

    Love this place. Thanks for all the info. I've read up numerous times since last year (or the year before?) and have a general handle (I think), but would like some help if possible. I've been shocking for the last couple of days, but the water hasn't turned grey and cloudy yet. Still green and cloudy. Also, my FC level seems to be holding fairly well. In fact, it went up on the last reading I took without adding anything?!! The only difference I know of is I took the reading from a different point along the wall and a few inches deeper.

    Here are my readings from today (using the K6000 kit):

    7:30 a.m.: FC =14, CC = 1, CYA = 27
    10:45 a.m: FC = 12, CC = 0 (sun shining on pool)
    12:45 p.m. FC = 15, CC = 0 (it allegedly went up without adding anything!)

    Here's some more background. We have a buried AG 24' diameter, 14500 gal pool with a 1.5 HP pump and sand filter. Late last summer, I got hit with a combo punch of a leak somewhere and an algae outburst. Well because of the leak, I wanted to let it drain down until it stopped, so I could hopefully find the leak (no luck, but I know where it stopped). And of course during this time, the water was too low to run the filter. By then summer was done, so I added bleach to get up to shock level for a while (no filter) and I think I pretty much closed the pool that way.

    So a few weeks ago (we're in Minnesota "ya know" ), I took the winter cover off to a dark brown swamp. I scooped leaves for several days, and got the water level back up so I could start the filter. I ran it that way for a few days before starting to shock because I wasn't sure how many more leaves were at the bottom. Then I started to "pseudo shock" before and after work (forgetting I should hit it hard and often at first and because I wasn't sure the brown was algae - kinda to see what happens). Then Friday I got more serious doing it at morning, noon, and night. And yesterday morning I woke up to FC of 8.5.

    Anyway, I am now to a dullish green color. And the biggest problem is my wife thinks it's not going fast enough and wants to add some "Green to Clean" diammonium stuff or get a "professional" here to do it. I am hoping that soon she will be a BBB convert! So, I'm confused on the FC readings and why it hasn't gone totally grey and cloudy yet.

    Any advice?
    24-ft round Radiant AG, fully in the ground, 14,500 gal
    Sand filter, 1.5 HP pump, vinyl liner
    9 months of winter, 3 months of tough skating!

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    Re: Green water, confused readings

    Check again on that kit number....tell us the correct number of the kit...it's important.

    We need to see full set of test results before we can help you accurately...post them like this....

    FC = ?
    CC = ?
    pH = ?
    CH = ?
    TA = ?
    CYA = ?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Jul 2011
    Location
    Northern MN
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    21

    Re: Green water, confused readings

    My bad. I have a TF-100 kit.
    Readings are:
    FC = 15
    CC = 0.0
    PH = 7.2
    CH =50
    TA = 75
    CYA = betw. 20-30

    Thanks for looking!
    24-ft round Radiant AG, fully in the ground, 14,500 gal
    Sand filter, 1.5 HP pump, vinyl liner
    9 months of winter, 3 months of tough skating!

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    Re: Green water, confused readings

    Well, those a very good numbers. Keep your FC right up around where it is now, brush, vacuum and clean the filter as needed.

    Your pool should keep clearing with daily improvement, even if small. Might be a few more days, depending on your diligence and your pool's filtering capability.

    Tell your wife to, "Chill out!" and then send us the address of the hospital where we can send you Get Well cards.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    JasonLion's Avatar
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    Silver Spring, MD
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    Re: Green water, confused readings

    It sounds like there might be a testing error of some kind going on. With CYA around 30 there should be a noticeable chlorine loss over a couple of hours while the sun is shining.

    Did you have the pump running the entire time? If the pump is off the chlorine may not have mixed in throughly.

    Algae doesn't always turn white/gray when it dies. Some kinds remain green.

    It can take a sand filter a week or more to clear up the water. However, if everything is working and you have killed all the algae there should be a visible improvement in the water from day to day. It might only be a small improvement.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Northern MN
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    Re: Green water, confused readings

    Thanks for confirming, guys.

    Yes, the filter has been running 24/7, so I would have assumed it had gotten mixed well, but maybe I took it from a dead zone or maybe there is a layer or something. I adjusted the return jet to maybe help. The FC did drop this afternoon a bit, so maybe it was a measurement anomaly. Anyway, I'll keep plugging away.
    24-ft round Radiant AG, fully in the ground, 14,500 gal
    Sand filter, 1.5 HP pump, vinyl liner
    9 months of winter, 3 months of tough skating!

  7. Back To Top    #7

    Join Date
    Jul 2011
    Location
    Northern MN
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    Re: Green water, confused readings

    Thought I'd give a quick update. Most importantly, my water is clearing. I could see the bottom, though the water is still green and cloudy. The sand filter is just taking a long time. My pressure gauge went out over the winter, otherwise I might try some DE in the filter to speed things along. I also thought about using some floculent that the pool store gave me when I bought the pool, but then thought better of it rather than introduce another variable.

    As for the questionable FC readings, I read the detailed instructions here (in Chem 201 maybe) and I hypothesize that I may have not been adding enough of the 870 powder. I am now adding two slightly-more-than-level scoops of the powder each time and seem to be getting more consistent, albeit very high, readings. I had been getting some near-zero readings (and adding more bleach accordingly). Finally I decided to double check the zero readings with the "daily, shades of yellow" tester in the kit. It turned dark orange - off the charts. Same with a test strip (dark purple). So I retested with the 870/871 and got an FC of 37! And I think that is accurate. Hopefully with a CYA of around 30, that high of a level isn't doing bad things. Since then, I've been testing and it has slowly been coming back down - it's at 20 now. Given it isn't burning off that quickly, I wonder if I killed off the algae earlier in the process but didn't realize it because the algae didn't have the decency to turn grey for me and because my sand filter is taking a while to clear it. Then when I started getting falsely low readings, I believed them and worked the FC up to crazy levels. Sound plausible?

    Anyway, I'm keeping at it and expect I'll get there sooner or later. Thanks again for the help and support.
    24-ft round Radiant AG, fully in the ground, 14,500 gal
    Sand filter, 1.5 HP pump, vinyl liner
    9 months of winter, 3 months of tough skating!

  8. Back To Top    #8

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    Location
    Northern MN
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    Re: Green water, confused readings

    Quick update: Yay, clear water and a happy wife! She says she's glad I listened to the forum experts rather than use the random "quick fix" chemicals she bought. Another BBB convert! So all in all, things are good! Still have some sand and dirt in the bottom to take care of, and have yet to pass the OCLT, but hoping that is tonight maybe. Then onto find the leak... Going to start by plugging the skimmer and the return, seeing if it still leaks and if so how much per day.

    Thanks for all the advice!

    PS: my FC readings have been consistent since I started using 2 scoops of the 0870 powder. Hopefully my accidental mega-chlorination didn't cause any ill-effects.
    24-ft round Radiant AG, fully in the ground, 14,500 gal
    Sand filter, 1.5 HP pump, vinyl liner
    9 months of winter, 3 months of tough skating!

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