from another website:

>Katie Bolek [2:47 PM February 21, 2005]
>katie@miox.com
>http://www.miox.com
>Another clarification on the test strips -- they are measuring >4.0 to 5.0 ppm of free chlorine, + or - 0.5 ppm.

So were looking for 5 ppm of free chlorine.