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Thread: PolyQuat and Shocking with Chlorine

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    haze_1956 is offline ** No working email address ** Thread Analyst haze_1956 0
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    Default Re: PolyQuat and Shocking with Chlorine

    Quote Originally Posted by CarlD View Post
    PolyQuat should NOT be used when fighting algae.
    You have said that on a quite a number of posts Carl !

    But what exactly do you base that statement on ?

    Ben even recommended using it against an existing bloom this year, although from what I gather it was as a last resort. However it did prove to be successful.
    .
    Last edited by haze_1956; 10-15-2006 at 04:48 PM.

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    chem geek is offline PF Supporter Whibble Konker chem geek 4 stars chem geek 4 stars chem geek 4 stars chem geek 4 stars
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    Default Re: PolyQuat and Shocking with Chlorine

    The theory is that PolyQuat disrupts the algae cell membranes thus bursting (or opening up) the cells and killing nascent algae. However, this is a somewhat slow process so it works well with algae trying to grow (stuff falling into the pool and trying to establish itself), but doesn't work well with large quantities of algae as it would take a lot of polyquat to deal with it (and is much more expensive than chlorine). Also, some types of established algae (and bacteria) form biofilms which are resistent to chemical penetration and would tend to block the PolyQuat from killing the cells underneath the biofilm. High chlorine concentrations will eventually breakdown such biofilms and utlimately get to what's lurking below (for black algae, brushing is also required).

    At least that's the theory.

    I think Ben's recommendation of using PolyQuat as a last resort is so that one has multiple actions going on at once. However, what we have recently discovered is that the shock levels in Ben's table are not sufficient for mustard/yellow algae, but we do seem to have figured that one out by using higher chlorine levels (about 1.0 ppm disinfecting chlorine).

    What I'm trying to figure out is what the proper application of PolyQuat would be when closing a pool since generally one uses a shock amount of chlorine and I am concerned that this would breakdown the PolyQuat defeating the purpose of using it. I'm not suggesting abandoning the use of PolyQuat -- just figuring out when it is most effective, perhaps when chlorine levels are lower (normal) rather than when shocking. So my proposal might be (with real-world verification) to use PolyQuat first at normal chlorine levels, wait a week, then use shock chlorine levels and close the pool, OR vice versa (shock levels of chlorine first, then when the chlorine drops to more normal levels, use PolyQuat and close the pool).

    Another option is to use 50 ppm Borates instead of PolyQuat and that seems to have the advantage of inhibiting algae without breaking down from chlorine the way that PolyQuat *may* do. It will be interesting to see if Borate levels are maintained over the winter with those people who are now using it.

    Richard

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    Jakebear is offline Registered+ Thread Analyst Jakebear 0
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    Default Re: PolyQuat and Shocking with Chlorine

    Quote Originally Posted by chem geek View Post
    The fact that users see chlorine levels drop rather precipitously while the CC only goes up a relatively small amount probably means one of the following:

    1) PolyQuat consumes (combines with) chlorine to perform some sort of chlorinated PolyQuat, but does not show up completely in the CC (TC) test.

    2) High levels of chlorine oxidize PolyQuat (i.e. break it down) which would explain the large drop in FC while CC doesn't climb very much. If this is the case, then it doesn't make much sense to close the pool with PolyQuat. Perhaps it's OK to use PolyQuat first, at lower chlorine levels, and then later (perhaps a few days or a week later) shock the pool with chlorine. I did read that it is recommended not to shock the pool within 48 hours of using PolyQuat.

    3) High levels of PolyQuat interfere with the FC test so that the chlorine level is still high but one does not know it from the test.

    If I were a betting man, I'd bet that #2 is what is going on.

    Richard
    So where do we go from here? I started with 5.0ppm FC and within 48 hours I was down to 2.8ppm. The PolyQuat dose was a start-up dose (Clean Pool) of 1oz per 1000 gal H2O. The question is since the Chlorine went down and has been restored ---- is there any Quat left??

    Is there a way to test to see if there is PolyQuat remaining? At $75.00 per gallon for 60% PolyQuat, it would be nice to know what’s happening.
    27038 Gallon InGround, Vinyl, DE filter.

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    haze_1956 is offline ** No working email address ** Thread Analyst haze_1956 0
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    Default Re: PolyQuat and Shocking with Chlorine

    As to closing a pool, at least where the water temp drops below freezing.

    Provided you use a solid cover that blocks the light, little or no algae should grow even at higher temps during fall. And any algae still alive should be killed over the winter by the low tempertures?

    Seems to me that if you put a winter cover a green algae pool, that algae should die over the Winter due to low temp and lack of light and you should find a clear pool with the bottom covered with dead algae come Spring.

    That seems logical to me, but does it hold true?
    .

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    Default Re: PolyQuat and Shocking with Chlorine

    Quote Originally Posted by Jakebear View Post
    So where do we go from here? I started with 5.0ppm FC and within 48 hours I was down to 2.8ppm. The PolyQuat dose was a start-up dose (Clean Pool) of 1oz per 1000 gal H2O. The question is since the Chlorine went down and has been restored ---- is there any Quat left??

    Is there a way to test to see if there is PolyQuat remaining? At $75.00 per gallon for 60% PolyQuat, it would be nice to know what’s happening.
    The change in chlorine of 2.2 ppm is 2.2 mg/liter or 1.2 moles per 10,000 gallons. The PolyQuat was 10 ounces (which I assume is fluid ounces liquid) which has 204 grams of PolyQuat which is 0.806 moles for one "poly" which has two nitrogen. Normally it takes at least 3 chlorine for 2 nitrogen to oxidize ammonia so this works out almost exactly correct in this case since (3/2)*0.806 = 1.21. In other words, it does appear that the chlorine indeed breaks down polyquat through breaking at the nitrogen and producing nitrogen gas (just as it does with ammonia). This would leave some other simpler organic compounds to oxidize, but these tend to be broken down much more slowly, possibly requiring sunlight and much more time. In other words, I would expect more chlorine to get used up, but over a longer period of time.

    So unless your numbers were just a coincidence, it appears that PolyQuat is broken down by chlorine very much as if it were ammonia (since it is, in fact, an ammonium compound). To me, this means that using PolyQuat in the presence of chlorine doesn't make much sense. Perhaps in the presence of smaller amounts of chlorine the PolyQuat forms something akin to monochloramine and that this is what is effective against algae, but that eventually this breaks down more completely (rather quickly, it seems) just as a monochloramine would break down to nitrogen gas.

    (I assumed that because PolyQuat is Poly{ oxyethylene (Dimethyliminio) Ethylene (Dimethyliminio) Ethylene Dichloride} that this is the following chemical formula:

    http://www.chemblink.com/products/31512-74-0.htm



    so molecular weight is 253.17 for each "poly" which has two nitrogen)
    Last edited by chem geek; 10-18-2010 at 08:57 PM.

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    CarlD's Avatar
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    Default Re: PolyQuat and Shocking with Chlorine

    I cannot argue with Chem_Geek's chemistry--it may well be that I've been wasting money using polyquat in large amounts prior to closing.

    But I have noticed too many times for it to be coincidence that adding polyquat will drop FC levels precipitously, but I've never gotten algae as a result. I've also found that 24 to 48 hours after the polyquat dose, that not only is the FC down, but that I can raise it back where I need it with predictable amounts: IE, 6% bleach will add 6ppm to 10,000 gallons.

    I am looking to get my water perfectly clean prior to closing, and wait till it's 60 deg or lower to shut down. (actually, I just completed this process).

    Is the poly causing the FC to fall by being metabolized by it? If so, is there any left when I then shock? If not, is there ANY point to using PolyQuat? Ben has given PolyQuat his recommendation only for prevention, and suggests avoiding ALL other algaecides.

    I'm not versed in chemistry, I've been going on what seems to work. If it's based on nonsense, and it may well be, I will change both my recommendations and my practice. Chem_Geek seems to be one of the most knowledgable chemistry geeks ( ) on the forum.

    But I have ALWAYS felt that shocking your pool up and keeping it up to the max FC level prior to closing is the way to ensure clean water in the spring, and I see no reason to change that recommendation.
    Carl

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    Default Re: PolyQuat and Shocking with Chlorine

    Quote Originally Posted by CarlD View Post
    Well, I just finished closing my pool today. I had my FC at 4, then added 48 oz of PolyQuat to my 19,200 gallon pool. FC dropped to 0. I then shocked it up, and, today, when I closed, FC was 13.5. I used Liquid Chlorine.
    The 48 oz in 19,200 gallons is equivalent to 25 oz in 10,000 gallons so 2.5 times the example I calculated earlier. So I would expect this PolyQuat to consume 2.5 * 2.2 = 5.5 ppm of chlorine so it is not surprising that it consumed all of your 4 FC. In theory, it would have consumed another 1.5 ppm of the amount you added to shock, though you've said that you didn't notice this when you then added chlorine to shock level, though 1.5 might not be that noticeable when shocking to 13.5 (it's a 10% error).

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    Default Re: PolyQuat and Shocking with Chlorine

    Quote Originally Posted by haze_1956 View Post
    As to closing a pool, at least where the water temp drops below freezing.

    Provided you use a solid cover that blocks the light, little or no algae should grow even at higher temps during fall. And any algae still alive should be killed over the winter by the low tempertures?

    Seems to me that if you put a winter cover a green algae pool, that algae should die over the Winter due to low temp and lack of light and you should find a clear pool with the bottom covered with dead algae come Spring.

    That seems logical to me, but does it hold true?
    .
    You also asked earlier if chlorine will breakdown detergents and the general answer is that chlorine will breakdown every organic compound in your pool eventually. It's just that this can be quite slow for certain organic compounds. Generally, chlorine is extremely fast (probably seconds) at combining with ammonia to form monochloramine. It is a little slower (probably a few minutes) to combine with nitrogenous organics to form chlorinated organics. It is then slower (probably minutes to hours) at breaking down monochloramine into nitrogen gas and may take even longer to break down the chlorinated organics, though sunlight might help this process. Pure organics not containing nitrogen would probably take the longest to breakdown.

    The PolyQuat isn't just a detergent. What mostly characterizes a detergent (and most clarifiers, for that matter) is a molecule that has a polar (charged) end and another that has a non-polar (uncharged or neutral) end. The non-polar side tends to embed in non-polar organics while the polar side has affinity for water. So the net effect is to cover or engulf non-polar organics presumably letting them filter out better -- that is, PolyQuat is really a clarifer and in fact was used as such before it became known that it was a good algaecide.

    You are correct that if you cover your pool to keep out sunlight and the pool water stays cold, then algae should not grow (I think the algae just becomes dormant in cold temperatures -- it probably doesn't get killed unless the water freezes which would burst the cells). However, I do seem to recall some photos on this forum where people have opened up their pool to a green mess and then shocked to get rid of it and I seem to recall such pools being covered. Perhaps the weather warmed up enough that the algae primarily grew just before the cover was taken off, and perhaps the cover wasn't opaque (I don't remember). At any rate, it doesn't take long for green algae to "bloom" and fill a pool.

    Richard
    Last edited by chem geek; 10-16-2006 at 03:00 PM.

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    Default Re: PolyQuat and Shocking with Chlorine

    I just wrote an E-mail to Buckman Laboratories regarding this issue of chlorine breaking down PolyQuat so we'll see if they respond. I'll keep y'all posted. We'll get to the bottom of this eventually.

    Richard

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    CarlD's Avatar
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    Default Re: PolyQuat and Shocking with Chlorine

    Quote Originally Posted by chem geek View Post
    The 48 oz in 19,200 gallons is equivalent to 25 oz in 10,000 gallons so 2.5 times the example I calculated earlier. So I would expect this PolyQuat to consume 2.5 * 2.2 = 5.5 ppm of chlorine so it is not surprising that it consumed all of your 4 FC. In theory, it would have consumed another 1.5 ppm of the amount you added to shock, though you've said that you didn't notice this when you then added chlorine to shock level, though 1.5 might not be that noticeable when shocking to 13.5 (it's a 10% error).
    That all adds up. I probably would have had FC of 15ppm.

    The next question (and Buckman may answer it) is whether PolyQuat and Chlorine are working together or fighting. Is there a residual that PQ leaves that continues to be effective against algae growth? Or is it gone?

    (BTW, if this gets more technical I'll move it to the China Shop.)
    Carl

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