Winter Water Temperature and Pool Chemical Balancing

[JPMorgan]

How cold does pool water get in winter temperatures in the north. I played around with Pool Math and noticed that at my current water temperature (about 70 degrees) and current readings, everything is in good balances (CSI = -.05). However if I drop the water temperature in Pool Math to 30 degrees I get a CSI of -.44 and at 10 degrees I get a CSI of -.66, which is out of safe range. Should I make adjustments to chemicals before closing to account for the colder water temperature and if so what temperature should I expect the water to reach if air temperature goes below 0.

 

[JamesW]

When was the last replaster?

 

[JPMorgan]

We have owned the pool for about 25 years and have never had it re-plastered. The pool had a painted surface when we became the owners and we have continued to paint it (every 5-6 years) with an epoxy paint.

 

[JamesW]

What are all of your balancing numbers?

 

[JPMorgan]

Currently they are:
FC - 5
pH - 7.5
TA - 90
CYA - 35
CH - 260

At 70 degree water temperature CSI is -.14; At 30 degrees CSI drops to -.54

 

[JamesW]

I would just let the pH get to about 7.8 and you should be good.

Paint is not the same as plaster. Paint might have some calcium carbonate filler, but I don't think that it needs the same CSI as plaster.

In cold water, all reactions slow down.

 

[JPMorgan]

Thank you.