I'm a new pool owner (as of September of last year) and ever since last season, my CYA has registered zero on my Taylor K-2006 test kit (meaning I fill the test tube all the way up and still clearly see the black dot at the bottom), which is wierd becuase the prior owner of my house used triclor tablets in two floaters as their prior means of chlorination. Anyway, I've read that the Taylor K-2006 kit cannot measure CYA concentrations of less than 30 ppm, so I'm not sure exactly how much CYA I have in my pool. If I was closer to 30 ppm, I'd be fine just leaving it where it is, but if it is truly zero, I would obviously want to add stabilizer.
I was reading some other threads on here that talked about diluting water samples when the concentrations exceed the maximum testing limit of the particular kit, and that got me thinking that perhaps I could evaporate a certain percentage of a sample to test for CYA of less than 30 ppm, since CYA does not evaporate.
For example, if you had a 10 ml graduated cylinder, you could leave it out in the sun for a few hours and see how far down the water level was, and use that percentage as a basis for your test. So if you start out with 10 ml of water and end up with 5 ml, you could test that sample and then multiple your result by 0.5, etc. So if your test result showed 35 ppm of CYA, your actual CYA would be 17.5 ppm. If your sample went from 10 ml to 8 ml, you could take your result and multiply it by 0.8. So, again, if your test showed 35 ppm, your actual level would be 28, and so on.
Anyone ever tried this? I guess it may be a bit overkill, but I'd really like to know where my CYA level is since I used tryclor tablets at the end of last season.