CYA Not Increasing as it Should

[bstway]

When I opened my pool this year the CYA was undetectable with my K-2006. This was not surprising since I keep it low and the pool level was dropped substantially over the winter. So, I added 24 oz of CYA I had left over from last year. After a week there was no change in the reading. I’ve since added another 36 oz over the course of the past few weeks. It just now registers barely 20 ppm. My CYA reagent and the 36 oz of CYA were purchased this year. PoolMath indicates the amount of CYA I’ve added should bring it from 0 to 40 ppm. I thought CYA had a shelf life of at least a couple of years if stored properly which it has. What do you think is happening here?

FC 3
pH 7.7
TA 80
CH 250
CYA 20

 

[cowboycasey]

Are you testing with Bright sunlight to your back outside and the CYA tester at waist level? I bet it is closer to 40 than you are seeing, you can try pouring it back and forth many times and glancing at the dot to get a better read

 

[kimkats]

what brand of CYA? I seem to remember there was one brand last year that was not adding up to what it should have been. Of course I forget the brand See if you can find a different brand and try it.

Kim:cat:

 

[bstway]

It's Leslie's Pool brand which worked fine last year.

 

[jblizzle]

How did you add the CYA?

 

[bstway]

All of the CYA was added via a sock in the skimmer.

 

[jblizzle]

Any backwashing of the filter while it was dissolving or right after? Just trying to think out loud

 

[bstway]

No backwashing of any type. I have been testing with my back to indoor light though. Tomorrow is supposed to be sunny. So, I'll do another test with my back to the sun. Hopefully, this is all user error.

 

[pooldv]

Here are some reference pics, https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36

There have been occasional reports over the years of CYA not registering with the theory that there is something wrong with the CYA. Either that or it disappears quickly. Sort of like UFO sightings hard to verify but it is what it is. Only answer is to add more CYA.

 

[duraleigh]

What test kit are you using?

 

[bstway]

K-2006

 

[Texas Splash]

As Casey mentioned above, it is very important to be outside under bright sunlight. That makes a huge difference. Even though it's supposed to be behind your back as you shade the viewing tube at waist level, that natural light really impacts the visibility of the black dot. We'll be curious to hear what you get today if the weather is nice there.

 

[bstway]

Who knows? Full sun today. The first try = 20ppm, second try = 35ppm, third try = 20ppm. I have no idea whether my eyes (brain) were playing tricks on me or what but the second try results did actually occur.