CYA Testing

[wjmano]

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]

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. 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 Levels 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.

 

[PoolGate]

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.

 

[Mdragger88]

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

 

[wjmano]

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!