Higher PH for winter?

[atttech-2]

PB turned over the pool a few weeks ago and I have been testing FC pH and TA every day and full test except CYA on weekends. I did the CYA twice once at day 10 and again at day 18, both came out the same so unless I have to drain I don't think I will test again for at least a month or more.

I have been playing with the numbers in pool math and noticed that with my current levels CSI readings are leaning towards "potential to become corrosive" mainly because the water is so cold (48F) if I put the temp at 80F things show "balanced". Since I can't raise the temp should I shoot for a pH 7.6 to 7.7 to compensate while the pool is cold or am I over thinking it?

FC 7.5 (same for 4 days running guessing due to cold)
CC 0
pH 7.5
TA 80
CH300
CYA 45 (PB added a bit more than I would have liked but workable)
Temp 48F

 

[BuckeyeChris]

I came to the same conclusion today. easier than raising TA, CH. Sitting at 7.7 and -0.2 for CSI (water temp 55). Just run the sheer. You should run your water features once in a while anyway to get fresher, chlorinated water through all the pipes.

 

[aussieta]

i keep my ph 7.8 to 8.0 over winter for the same reason

 

[duraleigh]

Back to OP's post...

1. Why are you running FC so high? That is above Pool School guidelines.

2. I am not a fan of csi but you are certainly in a comfortable range at -.46

Your numbers are fine (except for the FC being a little high) and I see no reason to change anything.

I would never suggest running pH above 7.8.....that's outside the guidelines we suggest.

 

[atttech-2]

FC being as high as it is was a mistake, I was keeping it around 5 but it got away from me on one add my wife did. I figured it would come down but it is being stubborn I guess because of the cold. i am sure one good storm will lower it a bit.

 

[duraleigh]

i am sure one good storm will lower it a bit.

I think I would maybe adjust your stenner down a bit. An FC of 2-4 would be fine for the cooler season and that CYA. (I'm cheating the numbers down just a bit from the FC/CYA chart as your stenner has almost the same affect as an SWG)

Storms should have little effect on FC.

 

[JoyfulNoise]

Your pool numbers look fine. All I would do is run your pH higher in the winter, target 7.7 or so. Calcium carbonate has higher solubility in water as the temperature decreases, it's called "retrograde solubility". That's why the CSI gets more negative as the temperature drops.

So you can either raise your TA or your pH to compensate for lower temperatures. As BuckeyeChris said, pH is easier to fiddle with than TA, so just let it go up a little. No one is swimming and the cold water is going to make pH rise very slow so you can easily go days without ever having to add any chemicals to the pool. Notice I said "adding chemicals" ... you still have to regularly test, that's always the right thing to do.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

 

[chem geek]

The pH will naturally be higher in colder water so it is perfectly reasonable to target a higher pH as the water gets colder. That keeps the water closer to being in balance for plaster surfaces. Colder water won't react as quickly so the risk is lower with a lower CSI but nevertheless it's usually easy to just target a higher pH where it probably wants to go anyway.