TA and CYA


LifeTime Supporter
Apr 20, 2008
NW Florida
Recent new member, my first post. I recently inhereted pool maintenace duties for my mother and I am grateful to the TFP forum for a quick learning curve. I have two questions that I haven't found directly addressed in the archive or stickies.

(1) I have both Taylor 2005 and LaMotte Pro-7 colorimeter test kits. I like the Pro-7 for FC and PH. I like the Taylor for ALK and CH titrations, and it's nice to have a double check. Would TPFers place confidence in home tests or the PS's when test results disagree (assuming no bad chemicals or testing technique on the TPFer end). Does the PS have a superior test "lab"? There are three stores in my area, and they don't get the same results. Sometimes off as much 100% with CYA, CH and ALK using the same sample.

(2) And secondly, to correct or not to correct TA for CYA? Taylor says yes, but notes that "some members of the pool/spa industry question its value." Not that important at high TA, but I am keeping my TA at 65 and my PH stays dead-on at 7.5/7.6 for weeks. I really like that. At a CYA of 45, is my TA of 65 really only about 50 ppm?

FC 5.0
CC .10 (little brats)
PH 7.5
TA 70
CH 300
CYA 45

The forum here has made maintenance so understandable (and affordable), I feel like I'm overlooking something.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
If you have a good test kit, which you do, always trust your own results over the pool store. The Taylor chemistry is really the gold standard of tests against which the others are compared. The ColorQ is wonderful at FC, CC, and PH as long as the FC and CH levels aren't too high. The big advantage of the fancy chemistry machines is that they can do the tests more quickly, but they are often less precise than the Taylor tests.

Around here we always use TA as read directly from the test. Which one you want to use depends on what you are using it for. The only real use for adjusted TA is when calculating LSI or when comparing to a source that is listing adjusted numbers. But as I said everything at TFP and my Pool Calculator list/use the unadjusted number straight from the test.