[gpodio]

Probably something wrong with the reference solution. Fleet is quite strong, in my log book I have "1ml of fleet will raise 10gal by 3.4ppm" so your test result sounds right. I use the Seachem test kit and it seems quite accurate, I can narrow it down to +-0.2ppm which is as accurate as I need it to be.

It should be easy to test however, just measure a sample of RO/DI water, then add 1ppm of fleet, and test again.

Regards
Giancarlo Podio

 

[gpodio]

You may have a bad box, mine develops the color nearly immediately as the instructions say it should.

Seachem is good at exchanging things so give them a call, they'll probably send out a replacement.

Giancarlo Podio