Closing chemistry recommendation

I have researched AND researched pool closing chemistry. After due diligence, here is my recommendation for IG vinyl liner with solid cover, freezing winter, and algae-free balanced water:

1) 2-3* nights before closing: Vacuum/brush and backwash if needed. Bring to shock level.

2) 1-2* nights before closing (next night): Add 60% polyquat at "visible algae" dose.

3) Night before closing: Check floor for debris, check filter pressure; adjust as needed. Raise FC back to shock level. Circulate 2 hours and lower level to below skimmer.

4) Close mechanics however you wish.

* Some people differ as to waiting 24 or 48 hours after polyquat addition. If waiting 48 hours, check FC after 24 hours to be on the safe side. Polyquat will lower fC.

I wonder about the effectiveness of Polyquat additions in high FC pool water. Typical a high FC will cause the polyquat polymer to become cleaved into shorter fragments. It's not clear that the effectiveness of the polyquat is degraded but the recommendation is to add the polyquat after the FC comes down to "normal" levels.

I'm not arguing with your methodology, just wondering if there's a better point at which to add the polyquat?

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Originally Posted by SunnyOptimism

I wonder about the effectiveness of Polyquat additions in high FC pool water. Typical a high FC will cause the polyquat polymer to become cleaved into shorter fragments. It's not clear that the effectiveness of the polyquat is degraded but the recommendation is to add the polyquat after the FC comes down to "normal" levels.

I'm not arguing with your methodology, just wondering if there's a better point at which to add the polyquat?

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I'd love to know the answer to this. I plan on closing later next week. :(

Quote:

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Originally Posted by SunnyOptimism

I wonder about the effectiveness of Polyquat additions in high FC pool water. Typical a high FC will cause the polyquat polymer to become cleaved into shorter fragments. It's not clear that the effectiveness of the polyquat is degraded but the recommendation is to add the polyquat after the FC comes down to "normal" levels.

I'm not arguing with your methodology, just wondering if there's a better point at which to add the polyquat?

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That is not MY recommendation.
I bring FC up to shock level, and when it holds there, add a quart of Polyquat.
I wait 48 hours, during which time FC plummets due to the Polyquat.
I then raise FC back up to shock level and close.
I always open to a clear pool unless I wait too long after the ice melts in the spring.

Somewhere ChemGeek responded to this issue after talking with one of the 'manufacturers' of polyquat. I believe he said that the shorter threads still do their job. But understanding ChemGeek is not my speciality!!!!

See this post where you can read the procedure from Buckman Labs. They also told me that when chlorine oxidizes Polyquat into smaller pieces, they are still fairly effective. They just won't act as much like a clarifier, but can still inhibit algae growth.

Ah, you wrote in English. ;) Your response was just basic enough for us non-chemgeeks to understand.

It is important information for those of us who ponder using polyquat on closing. The clarifying properties seem pretty insignificant at the end of the season.

I would love to see this info put out there for easier access on the Pool Forum.

Quote:

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Originally Posted by chem geek

See this post where you can read the procedure from Buckman Labs. They also told me that when chlorine oxidizes Polyquat into smaller pieces, they are still fairly effective. They just won't act as much like a clarifier, but can still inhibit algae growth.

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My winter closing procedure and spring opening results is a demonstration of that.

So here's how I'm reading the info in this thread-

You bring you water to shock level to clear it.

You wait some amount of time and then add polyquat

You wait a little longer and then raise your FC again and close.

The problem I see is that, based on the manufacturers recommended process, if you follow the CYA/FC relationship (as you should) then your shock level of FC is definitely going to cleave the PQ into smaller subunits unless you wait long enough after shock level for the FC to drop below 10ppm. If you look carefully at what the manufacturer says, they say to shock up to 5-10ppm and then "wait a few days" before adding the PQ. That tells me that the PQ is definitely going to cleave.

I guess the ultimate question is, at what FC does PQ start to cleave into smaller fragments and at what FC is the PQ's algaestatic properties completely destroyed? That last part would set the upper bound of how much FC you can have in the water when you add the PQ. Add the PQ too soon after raising the FC to shock level and you risk the chlorine burning up all your PQ.

Interesting stuff here.....

Quote:

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Originally Posted by SunnyOptimism

So here's how I'm reading the info in this thread-

You bring you water to shock level to clear it.

You wait some amount of time and then add polyquat

You wait a little longer and then raise your FC again and close.

The problem I see is that, based on the manufacturers recommended process, if you follow the CYA/FC relationship (as you should) then your shock level of FC is definitely going to cleave the PQ into smaller subunits unless you wait long enough after shock level for the FC to drop below 10ppm. If you look carefully at what the manufacturer says, they say to shock up to 5-10ppm and then "wait a few days" before adding the PQ. That tells me that the PQ is definitely going to cleave.

I guess the ultimate question is, at what FC does PQ start to cleave into smaller fragments and at what FC is the PQ's algaestatic properties completely destroyed? That last part would set the upper bound of how much FC you can have in the water when you add the PQ. Add the PQ too soon after raising the FC to shock level and you risk the chlorine burning up all your PQ.

Interesting stuff here.....

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I was wondering about that also.