Some Winter Advice (since it's here already!)

[tmarcoux]

Hi all!

I live in Austin, Texas and like nearly everywhere, we have been plunged into winter early. While we don't need to winterize our pools, I do need to do a winter change over, and this year, since I added an acid doser, I have some options which I am seeking some direction.

During the season, I have SWG which handle my Cl generation, and to combat the pH drift that it and my spa spillover creates, I added a Stenner acid doser. Everything has harmony!

Now my pool water temps are in to low 60's, the SWG is turned off. Here's my plan:

1. Add floater and pucks to maintain Cl (currently, my CA=40 and I can use this method to maintain Cl and raise CA to 80).
2. Adjust the acid doser down to maintain pH=7.3 (a bit lower due to CH=400).
3. Once CA=80, clean doser and switch from acid to Cl - dial it in to maintain Cl=2-3. Manually maintain MA
4. In the spring when temps hit 65+, switch everything back over to "summer mode".

Is this a sound strategy? The other alternative I see is to skip pucks and go directly to #3 and manually add CA. I have both pucks and conditioner.

pH=7.3
TA=50
CA=40
TC/FC=4
CH=400
Borates=40
Temp=62
very high copper in refill water so using Jacks Purple to try and mitigate (sequest = 6ppm - adding today to get to 12).

 

[easttn]

pH=7.3
TA=50
CA=40
TC/FC=4
CH=400
Borates=40
Temp=62

When I put your numbers into pool math, I get a CSI of -0.82 (Corrosion of plaster likely). I assumed you had 3500ppm of Salt since you have a SWG. When the water temp goes down its gets worse. It appears your going to have to adjust your water balance. How cold do you expect your water temp to get down to?

1. Add floater and pucks to maintain Cl (currently, my CA=40 and I can use this method to maintain Cl and raise CA to 80).
2. Adjust the acid doser down to maintain pH=7.3 (a bit lower due to CH=400).
3. Once CA=80, clean doser and switch from acid to Cl - dial it in to maintain Cl=2-3. Manually maintain MA
4. In the spring when temps hit 65+, switch everything back over to "summer mode".

1. While you can do this since you have a SWG (I believe I would quit at 60ppm CYA just to be safe) I see a potential problem. With a TA of 50 the trichlor pucks may cause your pH to go down.
2. See number 1. PH of 7.3 is going to be too low because of the CSI.

Your plan seemed good until the CSI threw a monkeywrench into it.

Also why do you need an automatic acid doser with that low of a TA? Just curious because I dont think I could trust something like that and it doesnt seem like you even need it with TA 50.

 

[ping]

Personally, I would just add the chlorine and acid by hand as it would not be very often during the winter.

If you decide to use pucks, keep a close watch on the pH and TA as pucks are acidic and tend to lower them and with the TA at 50 you might have some problems with the pucks.

 

[tmarcoux]

Easttn -

When I run the numbers on poolmath, I get -.67, which is likely to cause... I may have misunderstood recommendations for my other posts, but this approach was recommended because my plaster has been suffering from metal copper staining. Keeping pH a bit lower (and ultimately CSI) was recommended. For whatever reason, our city water is above EPA guidelines for copper and there's nothing I can do about it other than add sequestering agent. I will aim a bit lower as you suggested for CA - I can always add more later when the season hits.

Typically, once it gets cold, I don't need to do much, so as ping suggested, adding by hand is practical as well.

 

[easttn]

Cyanuric acid is abreviated as CYA instead of CA.

When I put these numbers in Pool Math:
16,000 gallons
pH 7.3
TA 50
CH 400
CYA 40
Salt 0 ?
Borates 40
Temp 62
I get CSI -0.61

You state you have a SWG in your info. How much salt ppm?
If I put 3500 ppm salt, I get a CSI -0.82
2500 ppm salt = CSI -0.77
I think you forgot to put your salt level in.

As far as the copper and pH goes, I dont know about that. Ive never seen a pH range suggested for copper. Maybe someone will clarify where you can keep your pH and safely keep your copper suspended with the sequestrant. Just because someone suggests to keep the pH lower doesnt necessarily mean to keep the CSI lower. Those are two different things. You can do other things to raise your CSI, like add TA (that will cause faster pH rise which then you can use your trichlor pucks as planned) and keep a lower pH, but the biggest factor in CSI is the pH.

It basically looks like your hung in between metal staining and corrosion of your plaster at this point.