Does pool temperature affect CYA readings?

[dmccarthy]

I read on one of my testing kits that the ideal temperature to get an accurate reading for CYA is between 70-80 degrees Fahrenheit. It said that if the temperature of the water is above that then it could artificially lower what the CYA levels are when you test and, in fact, your CYA levels could be higher than what the readings indicate. Is there any truth to that? If my outdoor pool is regularly over 85-90 degrees will that through off my readings?

Thanks.

 

[Divin Dave]

Thats a good question.

Im not sure if the higher water tems effect the CYA or if it does, by how much.

I do know for sure though that at lower water temps, the accuracy of the test is definetly effected and the test sample should be taken inside until it comes to room temperature.

No harm at all in doing that with warmer water either, if you are unsure. Or you could do 2 tests at the different temps, and compare them (which I have never done).
test the water right out of the pool. Then pour it from the test tube back into the bottle and take the bottle inside for a while. Hour or so should probably do it. Then test again.

 

[chem geek]

This question has come up before and Taylor answered it by saying that the test reads properly except for low temperatures (like 50ºF). Room temperature is fine and it is not true that higher temperatures would change the reading, at least not for the Taylor CYA test.

I think that some non-Taylor test kits may be more affected by temperature because those kits do not lower the pH when doing the test. The Taylor reagent has pH buffers that lower the pH to decrease melamine-cyanurate solubility. Otherwise, such solubility at room temperature is around 20 ppm and is temperature dependent. By forcing the pH low, the CYA is nearly all cyanuric acid, not cyanurate ion, so forces greater precipitation of mealmine-cyanurate.

 

[Divin Dave]

Awesome! Good info to know.

This question has come up before and Taylor answered it by saying that the test reads properly except for low temperatures (like 50ºF). Room temperature is fine and it is not true that higher temperatures would change the reading, at least not for the Taylor CYA test.

I think that some non-Taylor test kits may be more affected by temperature because those kits do not lower the pH when doing the test. The Taylor reagent has pH buffers that lower the pH to decrease melamine-cyanurate solubility. Otherwise, such solubility at room temperature is around 20 ppm and is temperature dependent. By forcing the pH low, the CYA is nearly all cyanuric acid, not cyanurate ion, so forces greater precipitation of mealmine-cyanurate.

 

[dmccarthy]

Great, thanks a lot!