Impact of cooler water on chems

[JonoVegas]

It's that sad time of year where our outdoor swimming season is coming to a close here in Vegas. Well at least spa season is "heating up"!

My water temps are in the 50's over the winter season here in Vegas. I understand and experience that FC doesn't drop much when the water temps are in the 50's, but does this cooler water temp (50's) impact PH movement, TA movement, CYA?

Thx,
Jono

 

[ajw22]

pH and Ta will likely be the same. You will probably see less CYA degradation with cooler water then when your water is over 90F.

 

[scottts]

Your CSI will drop with lower water temperatures even if everything else remains the same.

 

[thefloatqueen]

It's that sad time of year where our outdoor swimming season is coming to a close here in Vegas. Well at least spa season is "heating up"!

My water temps are in the 50's over the winter season here in Vegas. I understand and experience that FC doesn't drop much when the water temps are in the 50's, but does this cooler water temp (50's) impact PH movement, TA movement, CYA?

Thx,
Jono

Your FC will last longer in colder water temperatures, like you mentioned. TA and pH pretty much stay the same unless there’s heavy rain (I do not cover my pool). CYA stays more stable for me due to not having to add fill water, no splashout, etc. during the winter months when my pool is not being used and/or closed. I’ve heard the CYA test isn’t as accurate when water temperatures are below 60 degrees, though. Just thought I’d throw that in there lol

 

[ajw22]

If the water temperature is below 70F degrees let the water warm up inside before you do the CYA test.

The standard instructions to mix for 30 seconds is not enough time when the water is cold. You can either mix longer, or allow the sample to warm up to room temperature. Best solution is to allow the the sample to warm up first and then shake it for 30 seconds.

Taylor Technologies has run the pH, total alkalinity, calcium hardness, free chlorine, and cyanuric acid tests on known standard solutions at approximately 104°F, 75°F, 60°F, and 40°F. Only at 40°F did the CYA standard solution test higher than its actual value (after accounting for test variability). All other tests were unaffected by temperature differences.

The melamine solution that is used in the better tests is at low pH so as to force the maximum precipitation of melamine cyanurate since it is somewhat soluble at pH 7.0 with a solubility of around 20 ppm. There is no question that at colder temperatures it will take longer to precipitate.

 

[mknauss]

but does this cooler water temp (50's) impact PH movement, TA movement, CYA

You will continue to have evaporation, albeit at lower rates. So do test your pH every week or two. The TA increase from your fill water and the aeration from wind on the pool surface will still push your pH up over time.