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Thread: Can these chlorine measurements really be right?

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    robdac's Avatar
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    Can these chlorine measurements really be right?

    FC- 53 !!! (no, not 5.3)
    TC- 53
    PH- 7.5
    CH-450
    TA- 50
    CYA- 60
    Water Temp- 65

    Could this really be the chlorine level? I measured it with the TF-100 by carefully following the drop method. The included Taylor K-1000 shows readings off the Cl chart with only 1 drop of R-0600 instead of the prescribed 5. My Taylor K-1001, which uses the two chemical reagent method, also shows colors off the Cl chart.

    We have a pool guy because I'm a newbie learning this stuff but if the pool is really at 11 times where it should be on chlorine he's not going to have a job much longer. We haven't used the pool this winter and it's very well shaded with adequate stabilizer so maybe it has just been accumulating chlorine every week during servicing for the last 4+ months. The SWCG has been inoperative since we moved into the home last year. It's certainly clear, algae free, and blue!
    11K gal IG screened-in plaster pool w/ spa
    pentair 150 cartridge filter, Pentair Intelliflow VS pump,
    Aquarite AQR15 SWG, AquaCal Heatwave Heat Pump, TF-100 test kit

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    Re: Can these chlorine measurements really be right?

    FC can get that high. For CC, that's unlikely and I assume you mean TC. Are you using a 10 ml sample or 25 ml.?

    Did you use 53 drops or is that the number you get when using the multiplier?

    The multiplier for the 10 ml sample is 0.5 and the multiplier for the 25 ml sample is 0.2.

    See the link in my signature for a video of the test.

    Based on the chemistry numbers, I'm guessing that the chlorine is mostly from liquid chlorine? If yes, how much is added per week?

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    Divin Dave's Avatar
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    Re: Can these chlorine measurements really be right?

    Hi robdac,
    tell us your very recent history regarding adding chlorine.

    did you or the pool guy shock the pool in the last day or do? With what? How much?

    Im a bit leary of the result actually. To me that would seem somewhat incredible, but not to say it cant happen.
    very high FC will also make your PH test read a false high, and 7.5 Ph is not high. So Im leaning toward something went wrong with how your test was done.

    I would suggest to use the TF100 FAS-DPD and do it again.
    10 ml water in the tube
    add a heap of the powder R0870. The solution will turn pink. If it doesn't turn pink, there is 0 chlorine
    add 1 drop at a time while swirling of R0871 and count the drops.
    multiply the drops by .5 (point 5) and that is your FC
    [example: 10 drops is 5 ppm FC]

    If you added 106 drops of R0871, the FC would be 53.
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    Re: Can these chlorine measurements really be right?

    Everything certainly indicates your FC might be that high. I doubt the service guy ever tests for him to let it slip up that badly.

    How is he chlorinating? Tabs? Liquid? powder?

    Probably no real harm done in your type of pool but someone's money is certainly being wasted.

    You seem to have a pretty good grasp of the chemistry basics and are ready to take over your own pool management. Testing accurately is the key ingredient to good chemistry and I think you are doing that. We'll help every step of the way if you decide.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    robdac's Avatar
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    Re: Can these chlorine measurements really be right?

    Quote Originally Posted by JamesW View Post
    FC can get that high. For CC, that's unlikely and I assume you mean TC. Are you using a 10 ml sample or 25 ml.?

    Did you use 53 drops or is that the number you get when using the multiplier?

    The multiplier for the 10 ml sample is 0.5 and the multiplier for the 25 ml sample is 0.2.

    See the link in my signature for a video of the test.

    Based on the chemistry numbers, I'm guessing that the chlorine is mostly from liquid chlorine? If yes, how much is added per week?
    106 drops. 10ml sample size on the "Chlorine Only" cylinder. Liquid chlorine. They also use tablets once in a while as well. No idea how much they've been adding. Should have said TC not CC.
    11K gal IG screened-in plaster pool w/ spa
    pentair 150 cartridge filter, Pentair Intelliflow VS pump,
    Aquarite AQR15 SWG, AquaCal Heatwave Heat Pump, TF-100 test kit

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    Divin Dave's Avatar
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    Re: Can these chlorine measurements really be right?

    wow!
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    robdac's Avatar
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    Re: Can these chlorine measurements really be right?

    Quote Originally Posted by Divin Dave View Post
    Hi robdac,
    tell us your very recent history regarding adding chlorine.

    did you or the pool guy shock the pool in the last day or do? With what? How much?

    Im a bit leary of the result actually. To me that would seem somewhat incredible, but not to say it cant happen.
    very high FC will also make your PH test read a false high, and 7.5 Ph is not high. So Im leaning toward something went wrong with how your test was done.

    I would suggest to use the TF100 FAS-DPD and do it again.
    10 ml water in the tube
    add a heap of the powder R0870. The solution will turn pink. If it doesn't turn pink, there is 0 chlorine
    add 1 drop at a time while swirling of R0871 and count the drops.
    multiply the drops by .5 (point 5) and that is your FC
    [example: 10 drops is 5 ppm FC]

    If you added 106 drops of R0871, the FC would be 53.
    Unfortunately, I have no idea how much chlorine the pool service has been adding. I have added nothing to the pool since we moved in last summer. I don't know if they shocked it. I have had these readings for at least two weeks straight. Daily tests are always way off top the Cl color scale.

    I see your point about the Ph. At this point my primary concern is determining the actual chlorine level. The readings I'm getting seem very improbable.

    The 10ml sample of pool water immediately turned bright pink when I added the powder. I then added 106 drops of R0871 to turn it clear. This is the second time in two weeks I've done this test with similar results.
    11K gal IG screened-in plaster pool w/ spa
    pentair 150 cartridge filter, Pentair Intelliflow VS pump,
    Aquarite AQR15 SWG, AquaCal Heatwave Heat Pump, TF-100 test kit

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    Divin Dave's Avatar
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    Re: Can these chlorine measurements really be right?

    well you did the test right, and I trust the TF100 kit 100%.

    just.. wow!
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    robdac's Avatar
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    Re: Can these chlorine measurements really be right?

    Quote Originally Posted by duraleigh View Post
    Everything certainly indicates your FC might be that high. I doubt the service guy ever tests for him to let it slip up that badly.

    How is he chlorinating? Tabs? Liquid? powder?

    Probably no real harm done in your type of pool but someone's money is certainly being wasted.

    You seem to have a pretty good grasp of the chemistry basics and are ready to take over your own pool management. Testing accurately is the key ingredient to good chemistry and I think you are doing that. We'll help every step of the way if you decide.
    He's chlorinating with liquid and tabs. No tabs the last couple weeks. I've never seen him use a proper test kit of any kind. I've only seen him put drops of some type of reagent directly into the pool and look at the color it turned in the pool. I'm a self admitted newbie at this but I honestly don't think they know what they're doing.

    Thank you and my thanks to the others on this forum for their help. It's not a question of if, but when, I'm going to take over. We can do better than the service and I actually enjoy this kind of stuff.

    I emailed the service last week and specifically asked them to carefully check the chlorine levels. They serviced the pool and I've heard nothing back which is very disappointing.
    11K gal IG screened-in plaster pool w/ spa
    pentair 150 cartridge filter, Pentair Intelliflow VS pump,
    Aquarite AQR15 SWG, AquaCal Heatwave Heat Pump, TF-100 test kit

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    robdac's Avatar
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    Re: Can these chlorine measurements really be right?

    Here's what the Taylor K-1000 shows after adding only a single drop of R-0600 instead of 5 as advised by the instructions.2015-02-22 13.03.42.jpg
    11K gal IG screened-in plaster pool w/ spa
    pentair 150 cartridge filter, Pentair Intelliflow VS pump,
    Aquarite AQR15 SWG, AquaCal Heatwave Heat Pump, TF-100 test kit

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    Re: Can these chlorine measurements really be right?

    I think that your fc really is 53. It's time for you to take control of the chemistry. The current service people are not going to do it right.

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    Divin Dave's Avatar
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    Re: Can these chlorine measurements really be right?

    Congratulations on taking control of your own pool.

    You are ready now. No need to wait any longer.
    You have the test kit which is paramount, and you have the info available here to know where your levels should be.
    http://www.troublefreepool.com/conte...mmended-levels

    And you have the tool to know how much of what stuff to put in the pool in order to get to the recommended level.
    http://www.troublefreepool.com/calc.html

    you dont have to be an expert to take control. It really is as simple as following these recommendations.
    You can learn the chemistry over a period of time just like everyone else does.

    And as always, many folks here are eager to help out if you have questions about any of it.
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    Re: Can these chlorine measurements really be right?

    FC level is obviously extremely high. Your exact number may not be right, as there is a time limit on very high tests such that they tend to read higher than actual when you move along too slowly (which only matters when the drop count is high to begin with). However, the actual level must be really high or you wouldn't get into that situation in the first place. The OTO chlorine test also behaves exactly as described when FC is 30 or higher, which confirms the very high FC level.

    I'm reasonably confident that the CYA level is higher than you think it is. The higher the CYA level, the slower the FC level will come down. I also assume the water is cold, as cold water will slow chlorine loss. The enclosure will also slow chlorine loss. If the pool service has been using trichlor, it will have raised the CYA level significantly while in the process of getting FC up that high. I recommend doing the CYA test again, unless you did it very recently.

    You have two basic choices: let it come down slowly on it's own, or actively lower the FC level with a special FC lowering chemical. If CYA really is 60, then I would actively lower FC. But if CYA is indeed much higher, then it might be simpler to let FC fall on it's own.
    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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    Re: Can these chlorine measurements really be right?

    Because the pool is well shaded and the water is cooler, the FC loss rate is probably very low. I'll bet he's adding his usual amount of chlorine each week instead of scaling down to account for the shade and the lower water temperature. You might be losing only around 4% of the FC per day but he's still adding 2 ppm FC per day so the steady-state in that situation would be 2/0.04 = 50 ppm FC.

    Since he is apparently not doing any testing, you are lucky that your pH is a decent 7.5. With the use of tabs, the pH and TA could have crashed. The TA does look like it dropped from the tabs and that he didn't add any chemicals to compensate for that.

    With the FC that high, one would normally have the pH test look artificially too high. Perhaps the colder water is slowing that reaction down. If you wait longer for the pH test, does it start to get more purple to look like the pH is higher? If so, then the 7.5 may be a reasonably accurate reading.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Can these chlorine measurements really be right?

    I would suspect that part of the problem is that the service person probably just adds chlorine each visit with no knowledge of what the actual level is. In fact, if they test at all, they might be using a test that bleaches out, making them think that the chlorine is low.

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    robdac's Avatar
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    Re: Can these chlorine measurements really be right?

    Quote Originally Posted by JasonLion View Post
    FC level is obviously extremely high. Your exact number may not be right, as there is a time limit on very high tests such that they tend to read higher than actual when you move along too slowly (which only matters when the drop count is high to begin with). However, the actual level must be really high or you wouldn't get into that situation in the first place. The OTO chlorine test also behaves exactly as described when FC is 30 or higher, which confirms the very high FC level.

    I'm reasonably confident that the CYA level is higher than you think it is. The higher the CYA level, the slower the FC level will come down. I also assume the water is cold, as cold water will slow chlorine loss. The enclosure will also slow chlorine loss. If the pool service has been using trichlor, it will have raised the CYA level significantly while in the process of getting FC up that high. I recommend doing the CYA test again, unless you did it very recently.

    You have two basic choices: let it come down slowly on it's own, or actively lower the FC level with a special FC lowering chemical. If CYA really is 60, then I would actively lower FC. But if CYA is indeed much higher, then it might be simpler to let FC fall on it's own.
    A full test was performed this morning using the TF-100 as carefully as a newbie can before posting about the chlorine mess. I did the CYA three times by pouring the solution back into mixing bottle because it's so subjective. Got between 60-63 each time.

    My preference would be to fire the pool service and just let the FC drop on it's own over the next several weeks. Sound like a reasonable plan?
    11K gal IG screened-in plaster pool w/ spa
    pentair 150 cartridge filter, Pentair Intelliflow VS pump,
    Aquarite AQR15 SWG, AquaCal Heatwave Heat Pump, TF-100 test kit

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    JasonLion's Avatar
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    Re: Can these chlorine measurements really be right?

    Your FC level is almost certainly higher than Mustard Algae Shock level, which is the highest we normally recommend going. However it is well below the damage the pool structure levels, so waiting isn't too bad as long as you don't plan on swimming.
    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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    Re: Can these chlorine measurements really be right?

    So I just returned from the pool store where I asked them to check the chlorine level of a water sample. I told them that I measured the FC at 53. Two words come to mind; deer and headlights. Complete waste of time. They were able to tell me that my chlorine level was "a little high."
    11K gal IG screened-in plaster pool w/ spa
    pentair 150 cartridge filter, Pentair Intelliflow VS pump,
    Aquarite AQR15 SWG, AquaCal Heatwave Heat Pump, TF-100 test kit

  19. Back To Top    #19
    Divin Dave's Avatar
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    Re: Can these chlorine measurements really be right?

    I doubt they have the ability to test that high. The stores around here can only measure up to about 10. Above that, they have no clue

    Quote Originally Posted by robdac View Post
    So I just returned from the pool store where I asked them to check the chlorine level of a water sample. I told them that I measured the FC at 53. Two words come to mind; deer and headlights. Complete waste of time. They were able to tell me that my chlorine level was "a little high."
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    Re: Can these chlorine measurements really be right?

    My preference would be to fire the pool service and just let the FC drop on it's own over the next several weeks. Sound like a reasonable plan?
    Yes, it does. If FC doesn't come down to around 30 or so during the next week, I would consider manually lowering it by a partial drain and refill probably being the cheapest and easiest.

    If it does get to around 30, just keep letting it come down and read "The ABC's of Pool Water Chemistry" up in Pool School. It's a good place to start, then look at the FC/CYA chart in Pool School to find what chlorine level you should be keeping your pool.

    This stuff will get pretty easy and you have the right kit to get the precision in readings that you need.

    Ask questions.....we'll help.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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