CYA with 55 degree water

tcat

Well-known member
May 30, 2012
767
Austin, TX
#1
Just thought I'd pass this on, CYA is definitely effected by cold water. Tested mine today for 1st time in a month or so. Waited a minute and was fairly clear (CYA=0). Then I tested it again, held it in my palm for a minute (and brought it in the house), and presto, CYA = 40, approx. where I thought it should be. Got my Stenner set up, but FC has been above 7 for the past 2 or 3 weeks adding no Clorox. Waiting for it to get below 5 to start up the Stenner.

Anyone started draining their pool because of rain overflow, and forgot to switch it off? I was running on low draining about 4" of water, figured I had some time.... looked out 30 minutes later and down 4 inches (too much). Oh well, hopefully more rain before spring!
 

Divin Dave

TFP Expert
LifeTime Supporter
Oct 2, 2013
5,185
Longview, Texas
#2
Yeah, Im guilt of forgetting that I was draining some water out of the pool because of too much rain.
oops! :oops::taped:

Since then every time drain some water, I set the oven timer to buzz in 15 minutes to remind me!
 

JamesW

TFP Expert
Mar 2, 2011
12,677
#3
References say that cyanuric acid will test slightly higher at colder temperatures.

[Edit]
Actually, the references seem to be contradictory.

Do pool or spa water samples have to be at "room temperature" before testing begins?
With one exception, no. Our lab 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.
http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=86
The Cyanuric Acid (Stabilizer) test is perhaps the most inconsistent water test performed. Some of the problems of reporting and reproducing accurate Cyanuric Acid readings are:
1) Temperature of the sample. Try to keep and test the water sample at room temperature. The colder the water, the lower the test result.
http://www.aldenleeds.com/technical-advice/cyanuric-acid-testing/
There used to be a report that said

Water temperature is a source of error when testing cyanuric acid in pools. This primarily occurs with the turbidimetric tests. A 20° F increase in temperature from normal testing temperature can result in a 10-20% decrease in the CYA readings. A 20° F drop in temperature can result in a 10-20% increase in the CYA reading.

So if a water test sample reads 50 ppm CYA at 75° F, this same sample could read 60 ppm at 55° F. Conversely, this water sample could read 40 ppm at 95° F. It is a see-saw effect, as one goes up the other goes down. Table 1 gives an example of test results for both photometric and visual determinations of CYA as a function of temperature.
http://www.apsp.org/utility/showArticle/?objectID=1091
However, that report seems to have been removed. I think that the reference was from LaMotte. LaMotte does say this:

Cyanuric Acid: CYA tests are temperature sensitive. The best results are obtained when sample temperatures are between 70 and 80 degrees. In cold water, results may read high, while in warm water they may read low.
http://www.lamotte.com/images/pdf/testingtips/ColorQ Testing Tips.pdf
It could be that, in colder water, the test takes longer to complete. During the extra time, the test might have had sufficient time to complete, and the warmer temperature also sped up the reaction.
 

mikech

LifeTime Supporter
Aug 13, 2014
92
Seminole, FL
#4
Just thought I'd pass this on, CYA is definitely effected by cold water. Tested mine today for 1st time in a month or so. Waited a minute and was fairly clear (CYA=0). Then I tested it again, held it in my palm for a minute (and brought it in the house), and presto, CYA = 40, approx. where I thought it should be. Got my Stenner set up, but FC has been above 7 for the past 2 or 3 weeks adding no Clorox. Waiting for it to get below 5 to start up the Stenner.

Anyone started draining their pool because of rain overflow, and forgot to switch it off? I was running on low draining about 4" of water, figured I had some time.... looked out 30 minutes later and down 4 inches (too much). Oh well, hopefully more rain before spring!
I think I've noticed this effect. My pool was down to 60 deg. CYA is normally 45. I shook the sample vigorously for at least 45 secs, read it at 30. Repoured, re-shook, re-tested a minute or 2 later, got 40. Repeated and got 50! In the end I recorded it at 45, the same as it was. Tested again a week later and got 45 straight off.

Mike
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#5
It is definitely colder that gives the possibility of incorrect low results for the black dot disappearing test. Other CYA tests may react in other ways.

There are several ways to get the test to work reliably when the water is cold. The simplest is to warm the water sample up to room temperature before doing the CYA test.