How important is pool water temperture to the CYA test?

Splitshot

Active member
Apr 19, 2017
30
Hillsborough New Jersey
My water temp is 55 degrees. I read a post but cant find it about the CYA test and water temp. Not a noob pool owner, new to site/forums. Have been studying pool school and forums last 3-4 days and my re-education is a steep curve right now. Maybe my 60 year old brain is a bit overwhelmed..... I just don't think I am getting accurate reading. Here are last test #s
FC = 0.5
CC= 0.5
PH= 7.0
TA= 100
CH=125
CYA= >100

When I do the test I lose the dot before it ever reaches the 100 mark, there's a 1.8ml line on the tube and I lose it there. In addition when I opened/uncovered my pool I needed to add about 20% of fresh water via my hose, city water, to the pool due to displacement. That's typical for my pool. I want to be sure about test results before using the calculator to treat, or SLAM the pool, and get an idea of how many gals of chlorine or soda ash I need to be ready for all the steps. Pool does not have debris, brushing done every other day right now until I start the process. I don't get a lot of biologicals in the pool but it is pollen season, so there is that. Pool is clear, no cloudiness to my trained eyes, I've owned this pool for 18 years, and have been accused of being overly critical of its cleanliness, but its really crystal right now, and that's after just 3 gallons of bleach and 10lbs of ash. I hope this info I've provided helps with the answer.
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
3,959
CT
My water temp is 55 degrees. I read a post but cant find it about the CYA test and water temp. Not a noob pool owner, new to site/forums. Have been studying pool school and forums last 3-4 days and my re-education is a steep curve right now. Maybe my 60 year old brain is a bit overwhelmed..... I just don't think I am getting accurate reading. Here are last test #s
FC = 0.5
CC= 0.5
PH= 7.0
TA= 100
CH=125
CYA= >100

When I do the test I lose the dot before it ever reaches the 100 mark, there's a 1.8ml line on the tube and I lose it there. In addition when I opened/uncovered my pool I needed to add about 20% of fresh water via my hose, city water, to the pool due to displacement. That's typical for my pool. I want to be sure about test results before using the calculator to treat, or SLAM the pool, and get an idea of how many gals of chlorine or soda ash I need to be ready for all the steps. Pool does not have debris, brushing done every other day right now until I start the process. I don't get a lot of biologicals in the pool but it is pollen season, so there is that. Pool is clear, no cloudiness to my trained eyes, I've owned this pool for 18 years, and have been accused of being overly critical of its cleanliness, but its really crystal right now, and that's after just 3 gallons of bleach and 10lbs of ash. I hope this info I've provided helps with the answer.
With CYA over 90ppm, you should do the extended (diluted) test. 90ppm is about the upper limit of the test:
https://www.troublefreepool.com/content/220-CYA

I've never ran any controlled tests to see how much temperature effects the test, but the consensus here it that cold water will give false readings. I drop my 60ml sample bottle into a cup of hot tap water for about a minute or three when the water is below 70F. I do it just like I used to warm up my kids bottles, including a squirt on the wrist to see how warm the water is. When I feel it's warmer than 70F I proceed with the test
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,397
San Dimas, CA (LA County)
Funny you should mention that. There's an ongoing discussion about temperature and CYA testing in the Experts' Secret Lair. It appears the reaction is slowed, but not significantly, at low temperatures. We're talking only a matter of a few seconds longer for the stuff to cloud. If you mixed it for a minute, you've more than compensated for any temperature differences. Also, cold water would make you read lower than actual were it to be a problem, and you're having the opposite.

The question remains: how did the CYA get so high in the first place? The most common source is chlorinating with trichlor pucks. A close second is a weekly "shock" with dichlor powder. A distant third would be a pool "professional" doing the annual stabilizer addition without testing the current level first, but that can probably be ruled out in your case.

To get a closer reading for what your actual CYA level is, use the dilution method in Pool School - CYA
 
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