CYA Testing

wjmano

Gold Supporter
May 19, 2021
58
Wildwood, FL
Hello all. I've been doing my own testing for 2 months now. I use the TF-Pro kit.

My issue is interpreting my CYA results through the clear view tube. It other words, when has the black dot disappeared?

I try to stand outside with my back to the sun which creates a shadow in front of me and hold the tube at waist level. I do this and I find that I eventually lose sight of the dot, but partially because of a sheen off the top of the water. Then if I walk to a shaded part of my porch I can then see the dot and need to add more solution to lose sight of the dot. So...which is the correct result?

I worry about going with the lower result (more solution) and adding more stabilizer for fear of chlorine lock-up (although I don't know at what level this may occur) but I also have been having trouble maintaining my chlorine level, even though my SWG is running at 60% for 11 hours per day here in sunny Florida.

Thanks in advance for any advise out there.
Bill
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
40,608
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
It takes some practice, but stay outside under clear skies with the sun at your back. That natural lighting will reflect in/around the tube through the reagent while you look down from the top. Try not to squint or stare to the point you drive yourself nuts. :crazy: Glance, if you see the dot, add more reagent to the tube, and repeat until it's basically gone. Chlorine lock is nothing you need to be concerned about (pool store talk). Whatever your CYA settles to (60, 70, 80), as long as you have the FC balanced to it per the FC/CYA Chart you'll be fine.

It's possible the FC isn't holding because your CYA has been too low for a salt pool (below 70). If you have ANY doubt about potential algae (green or cloudy water), do an Overnight Chlorine Loss Test before you increase the CYA just in case you need to run a SLAM Process.
 
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PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
7,629
Damascus, MD
Pool Size
29000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
I suggest you buy the 50ppt reference solution on tf testkits. But, bottom line, the dot does NOT disappear. You should be able to see a faint outline of it. Testing until the dot truly disappears, and then adding more CYA to match the reading will result in a CYA level higher than you think.

1627474991569.png
 
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Mdragger88

Bronze Supporter
TFP Guide
Jun 1, 2018
6,957
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
Also remember you can pour the solution back into the little bottle and try the test again as many times as u need. I usually do it 3 or 4 times & then just use the average of those results. The 1st time I usually just squirt it in the tube till the dot is quite obscured then check to see what line I’m at.
The next couple times i fill it to each line then quickly check for the dot. I find it helps me gather a truer sense of where I really am & eliminates the urge to stare at it😁
 
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wjmano

Gold Supporter
May 19, 2021
58
Wildwood, FL
Thank you all for your help. I'm always pleasantly surprise at all the help offered here at TFP.

I will be trying some of the reference solution to gain more confidence in my interpretation of my real pool water. The good thing, is I don't think I've been off much, based on the comments here, but always good to get some additional guidance.

And good to know I don't have to worry about locking up my chlorine!
 
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