PolyQuat and Shocking with Chlorine

[Jakebear]

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.

[haze_1956]

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?
.

[chem geek]

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

[chem geek]

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

[fcfrey]

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

I guess you haven't heard anything yet from Buckman Labs. From all you've written it sure sound like Quat may be a waste if you follow the BBB method.

[chem geek]

I guess you haven't heard anything yet from Buckman Labs. From all you've written it sure sound like Quat may be a waste if you follow the BBB method.

I haven't heard from them yet and just sent a reminder E-mail. I doubt that PolyQuat is a waste at normal chlorine levels. The chlorine may only combine with PolyQuat relatively slowly at normal levels -- perhaps over a weeks time (given that it takes around 1-2 days at high chlorine levels) and the PolyQuat may be quite effective at preventing algae during that time. Also, I don't know yet if the chlorine combining with PolyQuat reduces its effectiveness (i.e. does it form a combination substance that is still useful or does it breakdown PolyQuat rendering it useless). So we'll still need to wait and see what Buckman says.

Richard

[chem geek]

I received the following response from Buckman Laboratories:

Mr. Falk:
 
Sorry about the delay in getting back to you.  I've been checking into some
literature references and trying to contact some of our water treatment
specialists to find some answers to your questions.
 
1)    The Polyquat 60 product that you mentioned is typically used along with
chlorine at normal use concentrations (low ppm levels of both substances) in
swimming pools.  Chlorine provides a faster kill of bacteria, while the
Polyquat 60 provides better control of algae as well as better water clarity.
The different advantages of these two pool treatments complement each other.
 
2)    While chlorine and Polyquat 60 have been shown to have very little
interaction at low concentrations, there can be some reaction or degradation
at higher concentrations.  For example, Polyquat 60 and bleach should not
be mixed neat, as an undesirable reaction would be expected to occur.
 
3)    In an alkaline solution containing an oxidizing agent, the polymer that
comprises the active ingredient in Polyquat 60 can be cleaved at the sites of
the quaternary ammonium groups, forming shorter polymer chains.  These
shorter chains are still cationic; and, according to some internal lab data
here at Buckman Laboratories, these shorter chains retain their biocidal
activity.  As the chains become shorter, the Polyquat test kit will not longer
respond to and detect them; however, the lack of a response by the test kit
does not necessarily indicate that the biocidal activity has been lost.
 
4)    In our recommended approach for winterization, the pool should be
"shocked" with about 5-10 ppm chlorine to destroy any lingering oxidant
demand, to remove any residual ammonia or chloramine, etc.  After a
couple of days, adjust the pH back to 7.2-7.6 and add Polyquat 60 at the
maximum rate allowed by the label.  This approach allows you to have the
maximum benefit from both chemicals.
 
If you have any other questions, please do not hesitate to contact us.
 
Tom McNeel
Principal Scientist
Buckman Laboratories International, Inc.

So there does appear to be consumption of chlorine by the PolyQuat (shock chlorine has high FC levels and increases the pH of the pool) and this is probably cleavage at the Nitrogen site, but the remaining chains are still effective as an algaecide. However, the recommendation is to first shock with chlorine (mostly to get rid of most organics and/or ammonia in the pool) and then wait for the FC to return to normal levels and make sure the pH is in the normal range. Then, add the PolyQuat in the recommended amount for closing the pool.

In addition to the E-mail, I talked with Dr. McNeel and asked about the method of action of PolyQuat on algae and he said that the cationic nature of the molecule (that means it has positive net charge) binds to and interferes with the negatively charged cell exteriors of most algae and bacteria and prevents the normal transport of food into the cell and waste out of the cell. This process is somewhat slow so it's fine for inhibiting algae, but not quite fast enough to quickly kill bacteria so chlorine is still required for disinfection. This method of action is for the hydrophillic (i.e. "water loving") PolyQuat molecules. There are other quarternary ammonium compounds that are hydrophobic (i.e. "water hating") that operate with a different method of action, but we didn't get into details on that.

He also said that while PolyQuat inhibits and kills algae, it does not harm people, either through skin exposure nor consumption (i.e. drinking pool water that has some PolyQuat in it). [EDIT] Dr. McNeel sent a follow-up E-mail saying that after adding PolyQuat, the circulation pump should be kept running for at least 24 hours to thoroughly distribute it through the pool. My guess is that the heavy molecular weight of the PolyQuat (it's a long-chain polymer) makes it slower to diffuse so lots of circulation is needed. [END-EDIT]

Thanks,
Richard

[chem geek]

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)

[CarlD]

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.