Testing CYA: something is wrong.

Jun 11, 2011
I just got my tf-100 today and I'm trying to use it for the first time, and I am having some issues. I just put a new liner in my pool 2.5 weeks ago so it is new water, I used triclor for the first 2 weeks and kept my fc right at 2ppm, then I decided to got with the BBB. My fc= 0, PH= 8.2 TA=200 and when I try to do the CYA test the solution I poured into the view tube stayed clear and I could see the dot the whole time all the way to the top. I then cut the pool water with tap water like it is suggested and it still stayed clear all the way to the top of the tube. I have done all of the test twice and got the same results (except the TA was 240 the first time but that was my fault). Not sure what I'm doing wrong but I would think 2 weeks of triclor would have made my cya that high. Thanks for any help. Nathan
Jun 11, 2011
OK, it really was all my fault I wasn't reading the tube right looks like I might have a CYA of 0, I will be adding some stabilizer now.


TFP Expert
Mar 2, 2011
3 pounds added to 26,000 gallons would add 13 ppm FC and 7.7 ppm CYA, which will read as zero.

Even if we assume an FC usage of 2 ppm per day, then the trichlor would have added about 17 ppm of cyanuric acid, which can still read as zero.

Jun 11, 2011
ok, I will get my CYA up and that should keep me from loosing all my chlorine to the sun each day. My pool is in full sun all day so I would think I would want a CYA of around 50 wouldn't I?


Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
I would add about 20ppm now (since you should have about 17ppm already). Then wait a week or so and check your level again. Then if you want to go up some more you can ... much easier to add than remove.