Different kinds of test equipment


In The Industry
Mar 21, 2008
Venice, FL
test strips

This is kind of off the subject but I noticed that there is talk about test strips. Doesn't anyone like them? I also bought a digital tester that tests chlorine, PH and ALK. Thoughts?


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
Test strips tend to give very imprecise results. Some of the digital testers are almost as good as the Taylor chemistry, but most of them are far worse. Tests using Taylor chemistry really are the best you can get short of laboratory equipment that requires a support staff.


A colormetric meter testing for chlorine using the DPD test still has all the limitations of DPD testing (Bleachout at FC levels much above 10 ppm) while the FAS-DPD titration can test FC levels up to about 50 ppm with an accuracy as great as .2 ppm. You certainly don't need any greater precision in a pool than that!.
pH using phenol red is pretty easy to test if you have a good testblock and good reagents such as Taylor or LaMotte. With practice you can read it pretty accurately without the comparator block.l
ALK tests done with a colorimeter will suffer the problem of the range of the meter itself. A titration test is open ended and can read as high as the amount of titrant that you have access to. Ditto for calcium hardness. I use a $1000 LaMotte colorimeter at work for water testing but I often back up the ALK and CH with Taylor titrations because of the inherent limits of colormetic testing, especially when ALK or CH is near the upper range of the meter or higher.

A true digital meter that uses an ORP electrode and pH electrode is only going to be as good as it's last calibration. These type of meters do not test ALK so I know it's not what you are talking about.
Test strips just don't have enough precision to give any really useful info for water balancing. If you want to try an interesting experiment and you have some money to waste get about 5 orf 6 different brands and kinds of strips and use them on the same water sample. The results will NOT be the same, even with some different strips from the same manufacturer (such as comparing a very popoular manufacturer's 5 way and 6 way!)