Polyquat Dosage

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#1
I've just shocked the pool again for mustard algae and have decided to try a continuing polyquat treatment.

What's the recommended continuing dosage for polyquat per 10,000 gallons? Does this vary by brand or just by the rated concentration?

Is there a brand that works better than others?

The local Leslie's doesn't appear to carry it, but they didn't recognize the term "polyquat." Can I successfully search a Leslie's for "benzalkonium chloride" and get a polyquat?
 

pooladdict

TFP Guide
In The Industry
May 14, 2007
819
New Brunswick Canada
#2
[oxyethylene (dimethylimino) ethylene (dimethyliminio) ethylene dichloride] Man that is a mouthful....you should be able to find it at any store really. Even walmart sells it under the HTH brand I believe. The bottle will tell you the proper dosing required.
 

duraleigh

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In The Industry
Apr 1, 2007
31,273
Sebring, Florida
#3
Chlorine and the SLAM process kills algae......it's the best method you can use.

The expense and results of using polyquat may be disappointing to you and certainly not necessary.
 

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#4
[oxyethylene (dimethylimino) ethylene (dimethyliminio) ethylene dichloride] Man that is a mouthful....you should be able to find it at any store really. Even walmart sells it under the HTH brand I believe. The bottle will tell you the proper dosing required.
Thanks, I'll try that formulation. Maybe even Leslie's has that, since I asked them to search for "n-alkyl-dimethyl benzyl ammonium chloride," per Wiki. I'm too far separated in time from chem to know whether or not those are the same things.

Thank you, but this is the third time this year, and fifth in two years, I've had to shock to mustard; at $50 each time for 10% Clorox, it hasn't been cheap. I'm growing weary of it and am minded to try something else.
 

pooladdict

TFP Guide
In The Industry
May 14, 2007
819
New Brunswick Canada
#5
Jay, do yourself a favour, get a good test kit, it will save you fortunes and you will know exactly where your readings are. TFP has a test kit that is the best price you can find. I suspect your pucks are driving up your CYA, and you are not able to maintain a high enough free chlorine reading.
 

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#6
Thank you, I have an FAS kit and have been using it for years. My shock level reached 39.5 ppm last evening, and it's been approximately that level since Thursday, four-and-a-half days ago. CYA was 40 before the shock, since I drained 60% of the pool two weeks ago to eliminate excess CYA.

You are correct that CYA was a problem five weeks ago, my last shock. I discovered that Lowes/Home Depot pucks are cheap, contain more non-chlorine content, and dissolve in the feeder too quickly. That required me to drain twice this year to alleviate CYA.
 

easttn

Well-known member
Jun 22, 2013
309
East TN
#8
Poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride] is what is called polyquat algaecide.
Alkyl () Dimethyl Benzyl Ammonium Chloride is what is called quat algecide.
Some algaecide are copper based.

The PolyQuat algeacides are what are recommended here but it is only used as a preventative and you really dont need it if you keep your FC level where it is supposed to be. It doesnt do any good while your slamming your pool. The chlorine does the work there.

From what I understand there is only one manufacturer of polyquat. It is then distributed to whomever and then they bottle it at different strengths. So one is just as good as the other but the 60% is usually the best deal.

Leslies Algae Control is polyquat
http://www.lesliespool.com/leslies-algae-control-pool-chemical/leslies-algae-control.htm
 

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#9
Poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride] is what is called polyquat algaecide.
Alkyl () Dimethyl Benzyl Ammonium Chloride is what is called quat algecide.
Some algaecide are copper based.

The PolyQuat algeacides are what are recommended here but it is only used as a preventative and you really dont need it if you keep your FC level where it is supposed to be. It doesnt do any good while your slamming your pool. The chlorine does the work there.

From what I understand there is only one manufacturer of polyquat. It is then distributed to whomever and then they bottle it at different strengths. So one is just as good as the other but the 60% is usually the best deal.

Leslies Algae Control is polyquat
http://www.lesliespool.com/leslies-algae-control-pool-chemical/leslies-algae-control.htm
Thanks, easttn - that's the info I need.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#12
You had this yellow/mustard algae before in December, 2012 so did you have a period of time when it was eradicated and it has now come back (i.e. did you have the algae last year)? It sounds like you cleaned the equipment before, but do you have pool lights and got behind the lights into the niche or removed any removable ladders to clean them?

If you are unable to eradicate the yellow/mustard algae or it gets reintroduced frequently then if you don't want to maintain a higher 15% FC/CYA ratio then you could use a phosphate remover as that works for all algae types, but it can be expensive especially if your fill water has phosphates.
 

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#13
I'd have to check my notes for 2013, but I suspect I shocked for mustard a couple of times that year and three times so far this year. (To be fair, the one six weeks ago I shocked for regular, not mustard, in order to see if I'd been misreading the signs and had been shocking for pollen, for instance; I had not been mistake - it was mustard.) Each time the removable equipment - hoses, heads, floats, etc. - got well treated. I have no ladders, but am unable to get behind lights, grills, and so forth, though I do what I can from the edge with a brush.

I keep FC normally at 5, though it falls occasionally to 4; I don't believe I can keep FC above 7, as some of the swimmers have asthma and high FC concerns them. I don't recognize the following term you used, i.e., "...maintain a higher 15% FC/CYA ratio...", unless you mean 15% of CYA 40 = 6ppm FC; that would be difficult as FC rises above 50.

I don't have a phosphate-level test. I would appreciate a pointer to where this removal is described.

Thanks.
 

pooladdict

TFP Guide
In The Industry
May 14, 2007
819
New Brunswick Canada
#14
I believe you were getting close to minimums a couple of time and its questioned whether you really did eradicate this algae completely. That's why 15% of CYA is recommended as your minimum until you are sure its gone. The phosphate treatment is only done when its higher then 2000 ppb. Phosphates can help algae continue to grow but if proper cl levels are maintained its rarely needed. Have you passed an OCLT?
 

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#15
A clarification, please. Is the 15% of CYA permanent, or is it until it passes an overnight chlorine drop test? That I can easily do, as we're no longer swimming this season.

No, it did not pass OCDT this cycle.
CYA 40, target FC >= 24
Began shock
29 Oct after dark - FC=25.5
30 Oct AD - FC=33
31 Oct not measured but probably ~30
1 Nov AD - 34.5
2 Nov Before Dawn - 30.0, shock continues
2 Nov AD not measured, probably ~35
3 Nov AD - 39.5
4 Nov Before Dawn - 36.0
(Unfortunately, ran out of R-0871 when old 0.75 oz containers (with new reagent) shattered, spilling the rest.)
I'll continue shock when reagent arrives.
 

pooladdict

TFP Guide
In The Industry
May 14, 2007
819
New Brunswick Canada
#16
I would wait til you pass OCLT, then once that happens, I would keep the 15% up for another week. That will ensure everything is dead.

Still have to vacuum and brush twice daily to ensure nothing hiding or hanging on. Ensure eyeballs are aimed properly to promote proper circulation.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#17
If you have yellow/mustard algae and have high algae nutrient levels in the pool, then it takes an FC level that is at least 15% of the CYA level to prevent that algae from growing. The normal Pool School level for regular green and black algae is an FC that is 7.5% of the CYA level. And yes, this would be permanent if you don't get rid of the algae or do something else to prevent its growth. So at 50 ppm CYA that would be an FC of 7.5 ppm. That's why I was giving you some other options. Though it is best to completely eradicate the algae through shocking at a higher level and exposing it wherever it exists, you haven't been able to do that so far.

The Taylor K-1106 tests for phosphates up to 1000 ppb. If you were to use a phosphate remover such as Orenda PR10,000 then you'd lower the phosphate level to 100 ppb or below.
 

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#18
Thank you, I appreciate it.

Does it make sense to combine the methods - phosphate remover and high chlorine?

We have just (nearly) completed a significant rain even in which I had to drain water from the pool to prevent it flooding the yard, so I am ready to begin again.

Edited to add: Leslie's confirmed my CYA = 40, but surprised me with a reading of Phosphates = 0.
 

Jaywalker

Well-known member
Dec 4, 2009
82
San Antonio, Texas
#19
Results post.

I didn't care for the "other chemicals" issues, so I continued, as advised, with the chlorine shock.

As I mentioned previously, I began the shock on 29 Oct 2014, had a pause in the middle due to a significant rain event in which I had to pump water from the pool to prevent overflow from flooding the yard.

On 7 Nov I did achieve a passing overnight chlorine drop test of 1.0, but decided to continue the shock in case that was an aberration or the result of a poorly-drawn or -measured sample.

On the morning of 11 November I achieved an OCDT result of 0.5 ppm, and consider that definitive. It did cost about $90 for the chlorine, plus whatever I had remaining from previous treatments, plus the cost of replacing anti-evapopration pool floats - $30-$50. It wasn't cheap, but this time I'm pretty sure I did kill the mustard algae, so if I get another infestation, I'm pretty sure it will be from another source than that which I did not kill in my pool. We'll see.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#20
Does it make sense to combine the methods - phosphate remover and high chlorine?
So it's a moot point given your latest shock and belief that you got rid of the algae, but if you do decide to reducer phosphates in the future then you won't need to have higher chlorine. It's either/or, you don't need to do both. With a lower phosphate level, algae grows more slowly so that normal chlorine levels will kill even yellow/mustard algae faster than it can grow.

If your phosphates were truly 0 as Leslie claimed, then you would have no algae growth at all. I'm pretty sure their number is bogus.