CYA test

[Beez]

Hi folks,

I'm trying to get a grip on the CYA level in my pool and I'm getting a little frustrated because I don't trust the results I'm getting. I have two different test kits: TF100 and the cheap HTH 6-way test strips that I bought while waiting for the TF100.

How accurate is the CYA test on the test strips? To my eye they read much higher than the presumably more accurate Taylor test.

My pool water is crystal clear, so I really don't have a problem. It's just that I would like to use the least amount of bleach that I can safely use, but how can I determine this without having an accurate CYA measurement?

Thanks,
Dave

 

[JasonLion]

The CYA test in the TF100 is the best one you can get. Test strips are often amazingly bad at measuring CYA. Trust the TF100.

 

[Beez]

The CYA test in the TF100 is the best one you can get. Test strips are often amazingly bad at measuring CYA. Trust the TF100.

OK, but even with the TF100 I don't trust the reading any closer than 10ppm and even then I don't feel confident with the result. Is this normal?

After several drains and refills, I think the CYA is now 50-60 ( down from 100+ ). I just wish I could be a little more accurate.

Thanks for the prompt response,
Dave

 

[frustratedpoolmom]

Have you seen this link?

http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=44

It may help you when performing the test.

Strips stink. Toss em.

 

[dmanb2b]

what does the level of CYA does the TF 100 test read? Your CYA may havse been well over 100 if all you tested with in the past is strips...they tend to stop at 100+

 

[Beez]

what does the level of CYA does the TF 100 test read?

Well that's part of the problem! Neither test seems definitive to my eye...all I can say is the test strips still read very high, close to 100, and I wonder if I'm influencing the Taylor result because I know I've drained and refilled.

I can say with certainty that the CYA has diminished with the drains, it's definitely under 100 now. I am yearning for accuracy. I wonder if I monitored the FC levels very closely if I could work backwards to obtain a CYA reading? The FC levels should not fall more than 1ppm from dawn to dusk, no?

 

[Beez]

I wonder if I monitored the FC levels very closely if I could work backwards to obtain a CYA reading? The FC levels should not fall more than 1ppm from dawn to dusk, no?

I've decided to answer my own question! That wouldn't work if the CYA levels were too high for my target FC level...

 

[PaulR]

I usually repeat the view-tube step of the CYA test 2-3 times to be confident of the point where the black dot disappears. It is just a very subjective test really not accurate to closer than 10ppm anyway.
--paulr

 

[Guest]

As far as test strips go I did an experiement on my own pool. I used the Lamotte colorimeter at work and got a CYA of 80 ppm (SWG). My TF100 also read 80 ppm. I then used a variety of LaMotte, Aquachek, Pooltime, and HTH strips and got CYA readings ranging from 0 ppm to 150 ppm. The only one that came close to the 80 ppm reading (which is correct based on the dosing of CYA I had done) were the HTH strips which are actually a rebranded Taylor test strip.