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Thread: Results confusing after shock.

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    Whatrymes's Avatar
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    Results confusing after shock.

    Hey, shocked the pool due to some visible green algae behind the ladder. All other symptoms were perfect including a clean filter.

    Using the pool calculator and with a residual FC level of 2.5 ppm, I added 1 lb of 65% cal-hypo (CH = 250), and 75 oz of 12.5% NaOCl to raise the FC to >16 ppm.

    1.) The water became very cloudy after adding the cal-hypo.

    2.) The FC level went higher than calculated to 19 ppm

    3.) The next morning the water was sparkling clear but some white sediment on the floor and the DE filter pressure rose 9 psi and flow was decreased.

    4.) After the overnight everything else is great:

    FC = 18.5
    OCLT = .5
    CC = <.5
    pH = 7.6
    TA = 120
    CH = 250
    CYA = 45
    15 X 30 X 3.6 Ester williams AGP
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    Haywood EC40C90 DE filter 1 HP pump
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    Richard320's Avatar
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    Re: Results confusing after shock.

    Sounds like everything is normal to me.

    The green you saw was just the tip of the iceberg - there was doubtless lots more algae just looking for a place to stick. You just zapped it and the white stuff is dead algae. And now the filter is catching it all and loading up. You've passed two of the three tests; the water is clear, the CC<.5, and you need to keep the FC up all day and run an overnight test tonight to see if you're done.

    You probably ought to backwash the filter, too. I expect the pressure will only get worse, especially if you vacuum up the algae carcasses.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Mod Squad Bama Rambler's Avatar
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    Re: Results confusing after shock.

    If you haven't baskwashed, I'd go ahead and vacuum and then backwash and recharge the filter. You'll probably have ot do it again but that'll get rid of a lot. Then as Richard said, run the OCLT.
    Dave J. TFP Moderator
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    Whatrymes's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by Richard320
    The green you saw was just the tip of the iceberg - there was doubtless lots more algae just looking for a place to stick. You just zapped it and the white stuff is dead algae. And now the filter is catching it all and loading up. You've passed two of the three tests; the water is clear, the CC<.5, and you need to keep the FC up all day and run an overnight test tonight to see if you're done.
    So last night's OCLT does not count??
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    Re: Results confusing after shock.

    whatrymes,

    I think he missed the oclt in your test results. Most people do not list it within their test results. If that OCLT result was from testing the night before and the next morning, is counts.
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    Mod Squad Bama Rambler's Avatar
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    Re: Results confusing after shock.

    We also like to see both sets of numbers. The evening and the morning results for FC & CC.
    Dave J. TFP Moderator
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    Whatrymes's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by Bama Rambler
    We also like to see both sets of numbers. The evening and the morning results for FC & CC.
    Sorry.

    Sunday 6:00pm:

    FC = 2.5
    CC = .2
    pH = 7.6
    TA = 120
    CH = 250
    CYA = 45

    Water was beautiful and sparkling but a small amount of green algae hiding behind the ladder.

    Added CL and it tested at 19ppm.

    Monday 7:00am:
    FC = 18.5
    CC = .2

    Thanks.
    15 X 30 X 3.6 Ester williams AGP
    10,800 gallons
    Haywood EC40C90 DE filter 1 HP pump
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    Re: Results confusing after shock.

    Not to steal Bama's fire here, but I think you are doing the test wrong. You do the OCLT by measuring at night after adding chlorine (about an hour after), then add no more before redoing the test in the morning. Looks to me like you should still be shocking!
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Whatrymes's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by linen
    Not to steal Bama's fire here, but I think you are doing the test wrong. You do the OCLT by measuring at night after adding chlorine (about an hour after), then add no more before redoing the test in the morning. Looks to me like you should still be shocking!
    I guess I don't write very clear, sorry.

    My FC was 2.5, shocked it to raise the FC to 19, this was all done Sun. pm. Next morning, Mon. am, tested again and the FC was 18.5 and CC ~.2. ??
    15 X 30 X 3.6 Ester williams AGP
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    Re: Results confusing after shock.

    Sorry I missed the 19 ppm in your post.

    Remember, shocking is a process and not a one time thing. If you still have algae, keep shocking.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Mod Squad Bama Rambler's Avatar
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    Re: Results confusing after shock.

    Sounds like to me you passed. You should be good to let the FC come back down to normal levels for yoru CYA.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    linen's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by Bama Rambler
    Sounds like to me you passed. You should be good to let the FC come back down to normal levels for yoru CYA.
    Hey Bama,

    The OP stills sees green:
    Water was beautiful and sparkling but a small amount of green algae hiding behind the ladder.
    Should he really stop shocking yet?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Mod Squad Bama Rambler's Avatar
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    Re: Results confusing after shock.

    I missed the still seeing green part. I thought they were past that. If they're still seeing green then either they didn't do the tests correctly of the green is not organic.

    I'm now thinking another OCLT is called for.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Results confusing after shock.

    I've passed an OCLT (multiple times) with algae in the pool and visible. Specifically mustard algae, and at normal FC levels. But when at shock level, I was failing. I would speculate that maybe the resistance of the mustard algae also means that it consumes less FC and so the OCLT can be passed anyway.

    Since Whatrymes is AT shock level, that may not apply here. Still, something to be aware of.
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    Whatrymes's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by linen
    Quote Originally Posted by Bama Rambler
    Sounds like to me you passed. You should be good to let the FC come back down to normal levels for yoru CYA.
    Hey Bama,

    The OP stills sees green:
    Water was beautiful and sparkling but a small amount of green algae hiding behind the ladder.
    Should he really stop shocking yet?
    Guess I'm a real dumb poster.

    I shocked the pool because I saw green algae behind the ladder. I don't see anything now.
    15 X 30 X 3.6 Ester williams AGP
    10,800 gallons
    Haywood EC40C90 DE filter 1 HP pump
    TF-100 Test Kit

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    linen's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by Whatrymes
    Guess I'm a real dumb poster.

    I shocked the pool because I saw green algae behind the ladder. I don't see anything now.
    And I'm a real dumb post reader Sorry about that.

    Sounds like you are good to go!
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Richard320's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by mynewpool
    whatrymes,

    I think he missed the oclt in your test results. Most people do not list it within their test results. If that OCLT result was from testing the night before and the next morning, is counts.
    That is correct.

    I'm not always my sharpest before 6 AM...
    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!

  18. Back To Top    #18
    Whatrymes's Avatar
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    Re: Results confusing after shock.

    Quote Originally Posted by Richard320
    Quote Originally Posted by mynewpool
    whatrymes,

    I think he missed the oclt in your test results. Most people do not list it within their test results. If that OCLT result was from testing the night before and the next morning, is counts.
    That is correct.

    I'm not always my sharpest before 6 AM...
    But thanks, you answered my original questions perfect.
    15 X 30 X 3.6 Ester williams AGP
    10,800 gallons
    Haywood EC40C90 DE filter 1 HP pump
    TF-100 Test Kit

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    Whatrymes's Avatar
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    Re: Results confusing after shock.

    OK, got into the pool today and took a real hard look behind the ladder. No visible algae present, yeeha! I'm planing on keeping the FC level to be no lower than 4 ppm with a CYA of 50.

    Thanks all.
    15 X 30 X 3.6 Ester williams AGP
    10,800 gallons
    Haywood EC40C90 DE filter 1 HP pump
    TF-100 Test Kit

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