What to do before closing

[FernTheBrute]

So I'll need to close my pool this weekend as we will get to freezing temps after that.

My current measures are about
FC: about 6-8
CYA: 50
ALK: 50
PH: 7.8 to 8.0 (whatever I do to lower it, it creeps back up there).

So here are my questions

1) Do I need to slam before closing? If so, I'm afraid my FC levels won't go back down sufficiently before the weekend. Plus, I currently don't have a test kit for high FC levels so i'd be eyeballing it...
2) I've read that a PH of 7.2 - 7.4 is ideal for closing. But by dropping to that PH, I'll definitely throw off my ALK. Then I will need to raise it and throw off my PH. What do I do with that?

 

[PoolStored]

It is not clear if you have an above ground or in-ground pool.

1) Do I need to slam before closing? If so, I'm afraid my FC levels won't go back down sufficiently before the weekend. Plus, I currently don't have a test kit for high FC levels so i'd be eyeballing it...

The point of raising to SLAM level FC is to have a reserve in the water for winter. I would raise FC to SLAM level 24 hours before closing and run the pump for the 24 hours, then close.

2) I've read that a PH of 7.2 - 7.4 is ideal for closing. But by dropping to that PH, I'll definitely throw off my ALK. Then I will need to raise it and throw off my PH. What do I do with that?

With a TA of 50, I'd leave the pH and close. You will be fine.

 

[FernTheBrute]

It is not clear if you have an above ground or in-ground pool.


The point of raising to SLAM level FC is to have a reserve in the water for winter. I would raise FC to SLAM level 24 hours before closing and run the pump for the 24 hours, then close.

With a TA of 50, I'd leave the pH and close. You will be fine.

Above ground.
Won't slamming neutralize the algaecide in my closing kit?

 

[PoolStored]

You didn't mention a closing kit. We don't recommend a closing kit. What is in the kit? Likely stuff you don't want or don't need in your pool.

Here is our guide on closing...

Closing (Winterizing) Your Above Ground Pool

Closing an above ground pool at season’s end should be a fast and worry-free process. Learn the basics of above ground pool winterization in easy steps.

www.troublefreepool.com

 

[FernTheBrute]

You didn't mention a closing kit. We don't recommend a closing kit. What is in the kit? Likely stuff you don't want or don't need in your pool.

Here is our guide on closing...

Closing (Winterizing) Your Above Ground Pool

Closing an above ground pool at season’s end should be a fast and worry-free process. Learn the basics of above ground pool winterization in easy steps.

www.troublefreepool.com

I haven't bought it yet. It's always super mysterious - "Arctic defense", "85% closing concentrate" and stuff like that.

I just read the article - if I went the algaecide way, I'd need to drop my FC before adding it, right?

 

[ajw22]

The only algaecide we recommend for pool closing is Polyquat 60.

Read Algaecide - Further Reading

 

[PoolStored]

I just read the article - if I went the algaecide way, I'd need to drop my FC before adding it, right?

No, re-read the article. Raise your FC to SLAM level for your FC 24 hours before closing, run the pump for the 24 hours. Then add the polyquat 60. You can brush the pool a bunch to circulate the polyquat, you can then let the pump run for about 4 hours after adding polyquat if you want to help distribute.

If you meant drop pH, not drop FC, then yes. Before raising FC, you should lower your pH to 7.4-7.6.

Skip the "closing kit."

 

[FernTheBrute]

No, re-read the article. Raise your FC to SLAM level for your FC 24 hours before closing, run the pump for the 24 hours. Then add the polyquat 60. You can brush the pool a bunch to circulate the polyquat, you can then let the pump run for about 4 hours after adding polyquat if you want to help distribute.

If you meant drop pH, not drop FC, then yes. Before raising FC, you should lower your pH to 7.4-7.6.

Skip the "closing kit."

If I raise my pool to SLAM level 24h before closing, it will still be at SLAM level when closing. It's not in the pool closing arcticle, but isn't Polyquat 60 killed off by high FC and vice-versa (its killing uses FC) ?

 

[ajw22]

If I raise my pool to SLAM level 24h before closing, it will still be at SLAM level when closing.

Does not matter. It will be close enough and more important it should be algae free.

It's not in the pool closing arcticle, but isn't Polyquat 60 killed off by high FC and vice-versa (its killing uses FC) ?

From Algaecide - Further Reading

Buckman Labs says that even if the Polyquat is broken down, it is still effective when used as an algaecide. Moderate to high levels of chlorine break down Polyquat but it still only transforms the formula into shorter chain polymers that are still just as effective.

 

[FernTheBrute]

Does not matter. It will be close enough and more important it should be algae free.



From Algaecide - Further Reading

Buckman Labs says that even if the Polyquat is broken down, it is still effective when used as an algaecide. Moderate to high levels of chlorine break down Polyquat but it still only transforms the formula into shorter chain polymers that are still just as effective.

Very interesting read, thanks!
Wouldn't you happen to know where I could get polyquat 60 easily in Canada?

 

[PoolStored]

Search "polyquat 60 canada"

you want this active ingredient -
Poly{oxyethylene(dimethyliminio)Ethylene (dimethyliminio)ethylene dichloride}; 60% concentrate in water

If it says -
alkyldimethylbenzylammonium chloride. That is a linear quat algaecide and you do not want that.

 

[FernTheBrute]

Search "polyquat 60 canada"

you want this active ingredient -
Poly{oxyethylene(dimethyliminio)Ethylene (dimethyliminio)ethylene dichloride}; 60% concentrate in water

If it says -
alkyldimethylbenzylammonium chloride. That is a linear quat algaecide and you do not want that.

Found it at the hardware store, thanks!
Is there a good way to know the correct dosage for pool closing? I have a 18 000 L of which I'll remove about 2/3 of water, so I guess it should not take much.

 

[PoolStored]

Read the instructions on the bottle for maximum dose. Use 1/3rd of your pool volume and follow the instructions.

 

[FernTheBrute]

Search "polyquat 60 canada"

you want this active ingredient -
Poly{oxyethylene(dimethyliminio)Ethylene (dimethyliminio)ethylene dichloride}; 60% concentrate in water

If it says -
alkyldimethylbenzylammonium chloride. That is a linear quat algaecide and you do not want that.

Turns out I had a bottle in my shed
But it's been there for a year and went through a winter, I'll get another one.

Regarding the best chlorine level for usage, I'm currently at 40 of CYA, so 5-7 chlorine for day to day and 16 for slam. Do I drop down to 5-7 before adding the algaecide or stay somewhere between that and 16?
And regarding dosage, the bottle says 100ml max dose per 10 000L of water. That seems not much - is it on par with similar products?

 

[PoolStored]

Just take FC to 12 and keep it there until you are ready for the PQ60. Add the PQ60 24 hours before closing.

 

[FernTheBrute]

So I got thinking... I've been running with a low-ish alkalinity level most of summer (45-50), anything above that and I have to add acid every two days when on liquid chlorine. If I raise my chlorine level to 10-12 before closing the pool for winter, while maintaining a proper Ph, won't this Ph tend to crash as the chlorine goes away, especially since I don't have much alkalinity buffer?
Should I make sure my Ph and alk are on the high side before closing?

 

[PoolStored]

Additions of liquid chlorine, or falling chlorine levels, have no impact on pH.

Rain/Snow has a pH between 5 and 5.5. If you get lots of snow/rain over the winter, which may lower your pH a bit. For the most part, I would not worry about it. If you are concerned, raise your TA to 60 using baking soda. Use pool math to calculate the amount.

Good to go!

 

[FernTheBrute]

Additions of liquid chlorine, or falling chlorine levels, have no impact on pH.

Rain/Snow has a pH between 5 and 5.5. If you get lots of snow/rain over the winter, which may lower your pH a bit. For the most part, I would not worry about it. If you are concerned, raise your TA to 60 using baking soda. Use pool math to calculate the amount.

Good to go!

Isn't the general recommendation to drop Ph to 7.2-7.3 before a SLAM because liquid chlorine, with its high Ph of around 13, raises the general. Ph of the pool?

 

[ajw22]

Isn't the general recommendation to drop Ph to 7.2-7.3 before a SLAM because liquid chlorine, with its high Ph of around 13, raises the general. Ph of the pool?

PH - Further Reading

www.troublefreepool.com

It is a myth that liquid chlorine will raise pH. The myth is based on a misunderstanding of chlorine chemistry.

Adding liquid chlorine to water can cause a temporary increase in pH which is usually offset by the chlorine reacting with organics and biological matter which are acidic (creates a proton) reactions. Thus, on balance, the net chlorine reactions are pH neutral.

Most retail and commercial liquid chlorine products contain a small excess of lye from the manufacturing process but this amount of OH- is minimal and does not change the pH with normal levels of liquid chlorine use.

If one were to add significant amounts of liquid chlorine (for example, raising the pool water chlorine concentration to SLAM FC levels), then the pH rise would need to be offset by an initial lower of the pH with acid. This is why TFP requires a pool owner to adjust their pH down to 7.2 prior to starting the SLAM Process.

Adding liquid chlorine DOES increase the pH at first, however as it's used up the acid that's created lowers it back down to where it was before......thus equaling each other out making it pH neutral.

 

[PoolStored]

@ajw22 is spot on...Chlorine, net net is pH neutral.

Lowering pH for the slam is because high pH can precipitate metals that can cause staining, can cause cloudiness from over-saturation of calcium carbonate, and at much higher pH the active chlorine level goes down significantly. Active chlorine level is also significantly improved with CYA in the water, hence the recommendation for 30ppm CYA.

HOCL is the active chlorine in pool water...the red lines below. If we want to maximize the amount of HOCL in the pool water to kill algae during a SLAM, a safe pH of 7 to 7.4 will maximize the % of HOCL in the water. Or, better said, the further we can keep pH to the left on these graph, the better.



Wouldn't, based on these graphs, it be better to SLAM with lower CYA because the % of HOCL is higher? Yes, but the half life of chlorine is about 1/2 hour with 0 CYA, and about 6 hours with CYA of 30. At 0 CYA you would use a lot of chlorine.