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Thread: Ion Chromatography Results - Cloudy Pool

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    Ion Chromatography Results - Cloudy Pool

    Hi all,

    I'm new to the forum, but not new to owning a pool.
    The algae in my pool got way out of control early this season. It is a typical kidney-shaped in ground pool. Bromine is the sanitizer.
    Before shocking it, I decided to satisfy my curiosity and test the sample using the ion chromatograph at school. I also tested for free and total Chlorine. Here are the results:

    Free Cl: 1.85 mg/L
    Total Cl: 2.05 mg/L

    Ion-Chromatography:
    Chloride: 158 mg/L
    Sulfate: 248 mg/L
    Phosphate: 3.9 mg/L
    Nitrate: 0.16 mg/L

    Bromide was also detected by the IC- but the machine was not calibrated with a bromide standard, so it did not calculate the concentration. I've attached the PDF with the graph and outputs.

    For the pool chemistry experts out there, what do you think?

    My thoughts are that phosphates are quite high, providing ample nutrients for algae to grow. The high concentration of sulfates is evidence of using lots of algaecide in the past.

    2016-07-05.pdf

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    JoyfulNoise's Avatar
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    Re: Ion Chromatography Results - Cloudy Pool

    Welcome

    The IC results, while perhaps fun to perform, are not useful in the slightest. You can worry about phosphates later, they are not at all important right now.

    Right now, your biggest concern is not having a proper test kit. Go and purchase one of the recommended test kits (either a Taylor K-2006C or a TF-100 with XL option from TFTestkits.net) and we'll help you clear the pool. I very much doubt that your chlorine/sanitizer levels are at all adequate and unless we know your CYA and other levels, there is no advice we can give.

    For now you can stop using any stabilized, solid chlorine products and just pour a half gallon of unscented regular bleach (8.25% Clorox) in your pool water until your kit arrives. Then we can work from there. While you wait you can add your pool details to your signature and read Pool School to learn what it is WE TEACH pool owners to do. If you follow the TFP methodology of pool care, you will have a clean and clear pool that is trouble free and will not require any form of chromatography analysis at all.

    Good luck,

    Matt

    - - - Updated - - -

    Also, do you intend to operate your pool as a bromine pool? You would be well-advised to consider converting to chlorine as bromine is expensive and difficult to control in open pools. Chlorine is much cheaper and more effective for pools.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Piolin's Avatar
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    Re: Ion Chromatography Results - Cloudy Pool

    Welcome to the forum!!! Good advice, I just want to add for you to read pool school and see how we care our pools, good luck... This is the most friendly forum I ever enrolled and very helpful, again welcome!!!

    Starting day 5/25/2015 INTEX AGP 24'x12'x54" 8,400 gal, with salt and borax, INTEX 3,000 GPH pump with 16"sand filter, WM Hayward Skimmer, Intex SWG CG-28669, 1 1/2" hard plumbed PVC, Lil' Shark Vacuum With Leaf Canister, TF100 test kit, speed stir, K-1766 Taylor salt test
    8,400 gal Intex, 3K GPH pump, 16" sand filter, SWG CG-28669, TF100 test kit, speed stir, K-1766 Taylor salt test.

    The corner stone of TFP
    Pool School - Chlorine / CYA Chart

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    Re: Ion Chromatography Results - Cloudy Pool

    Thanks for the quick replies! To be clear, I am not asking how to go about clearing my pool. I am familiar with the pool school, and I'm not about to spend a week draining and refilling the pool to switch it to chlorine. As originally stated, I am just curious about these results and if they can be interpreted to mean anything.

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    JoyfulNoise's Avatar
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    Re: Ion Chromatography Results - Cloudy Pool

    Quote Originally Posted by lucask View Post
    Hi all,

    I'm new to the forum, but not new to owning a pool.
    The algae in my pool got way out of control early this season. It is a typical kidney-shaped in ground pool. Bromine is the sanitizer.
    Before shocking it, I decided to satisfy my curiosity and test the sample using the ion chromatograph at school. I also tested for free and total Chlorine. Here are the results:

    Free Cl: 1.85 mg/L
    Total Cl: 2.05 mg/L

    Ion-Chromatography:
    Chloride: 158 mg/L
    Sulfate: 248 mg/L
    Phosphate: 3.9 mg/L
    Nitrate: 0.16 mg/L

    Bromide was also detected by the IC- but the machine was not calibrated with a bromide standard, so it did not calculate the concentration. I've attached the PDF with the graph and outputs.

    For the pool chemistry experts out there, what do you think?

    My thoughts are that phosphates are quite high, providing ample nutrients for algae to grow. The high concentration of sulfates is evidence of using lots of algaecide in the past.
    The proximate cause of any algae bloom has more to do with inadequate sanitizer levels than high nutrient levels. As long as a pool remains properly sanitized, it does not matter what your nutrient levels are. This is why bromine sanitation does not find wide spread use in outdoor pools as most people find it to difficult to maintain a proper bromine level given the high loss rates of bromine in open waters. With wildly fluctuating sanitizer levels comes the inevitable algae bloom. Any slight advantage in sanitation that bromine might have is more than offset by its higher costs both in terms of chemical costs and lost time.

    Sulfates can arise from several sources. If you are using a copper sulfate based algaecide then you are getting the doubly ill effects of excess sulfate and the potential for copper metal stains. Polyquat-60 would be a better choice of algaecide as it leaves behind little in the way of contaminants. One can also get sulfate build up from the use of MPS non-chlorine shock to regenerate bromine from the pool's bromide bank. Sulfates are extremely detrimental to plaster and concrete surfaces as sulfate attack starts to occur at around 300ppm (just about where you are right now). As well, high sulfate and high calcium hardness can lead to calcium sulfate (gypsum) scaling. This type of scale is difficult to remove as it firms needle like crystals that do not dissolve even when exposed to acids.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Ion Chromatography Results - Cloudy Pool

    Quote Originally Posted by JoyfulNoise View Post
    The proximate cause of any algae bloom has more to do with inadequate sanitizer levels than high nutrient levels. As long as a pool remains properly sanitized, it does not matter what your nutrient levels are. This is why bromine sanitation does not find wide spread use in outdoor pools as most people find it to difficult to maintain a proper bromine level given the high loss rates of bromine in open waters. With wildly fluctuating sanitizer levels comes the inevitable algae bloom. Any slight advantage in sanitation that bromine might have is more than offset by its higher costs both in terms of chemical costs and lost time.

    Sulfates can arise from several sources. If you are using a copper sulfate based algaecide then you are getting the doubly ill effects of excess sulfate and the potential for copper metal stains. Polyquat-60 would be a better choice of algaecide as it leaves behind little in the way of contaminants. One can also get sulfate build up from the use of MPS non-chlorine shock to regenerate bromine from the pool's bromide bank. Sulfates are extremely detrimental to plaster and concrete surfaces as sulfate attack starts to occur at around 300ppm (just about where you are right now). As well, high sulfate and high calcium hardness can lead to calcium sulfate (gypsum) scaling. This type of scale is difficult to remove as it firms needle like crystals that do not dissolve even when exposed to acids.
    Thanks for that information. I'll try to avoid algae for the rest of the season by bumping up the bromine tablets with liquid chlorine. I'm guessing it would be unnecessary to try reducing phosphates?

    It is a vinyl pool- but still good to know about sulfate concs. Hoping to avoid algaecide for the remainder of the season.

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    Re: Ion Chromatography Results - Cloudy Pool

    Can your machine test for 5-5 dimethylhydantoin?

    That's what's in bromine tabs and because it binds up some of your bromine, it reduces the effectiveness of the bromine. Dealing with the dmh is more important than the phosphates.

    You really need to stop using br tabs. You can switch to a chlorine source such as liquid chlorine or salt system without draining. It will still be a bromine pool, but your dmh won't increase.

    If the machine can't test for dmh, bromide levels can help determine dmh because they're both added by br tabs.

    How many pounds of br tabs have been added total since the pool was last filled?

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    Re: Ion Chromatography Results - Cloudy Pool

    Quote Originally Posted by JamesW View Post
    Can your machine test for 5-5 dimethylhydantoin?

    That's what's in bromine tabs and because it binds up some of your bromine, it reduces the effectiveness of the bromine. Dealing with the dmh is more important than the phosphates.

    You really need to stop using br tabs. You can switch to a chlorine source such as liquid chlorine or salt system without draining. It will still be a bromine pool, but your dmh won't increase.

    If the machine can't test for dmh, bromide levels can help determine dmh because they're both added by br tabs.

    How many pounds of br tabs have been added total since the pool was last filled?
    Not sure if the instrument can test for DMH- or at least not in the configuration the test was run in.
    It's been about five years since replacing the liner when it was completely drained. The water level is drawn down below the pipes each winter. So while I can't estimate a specific quantity of bromine pucks, it is several seasons worth.

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    Re: Ion Chromatography Results - Cloudy Pool

    Using all bromine tabs is roughly equivalent to using all trichlor tabs. The level of DMH gets too high. A drain and refill, or multiple partial drains and refills, are about the only way to get the level of DMH down.

    A full drain and refill is probably not practical unless you want a new liner.

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    Re: Ion Chromatography Results - Cloudy Pool

    Thanks for the very useful insight. There isn't nearly as much info out there on bromine compared to chlorine.

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