Free Chlorine/Bleach Test Strips, 0-1000 ppm [Vial of 25 Strips]

The color code chart is it range of purples in the test strips turned blue. I used another brand test strip that work correctly to be sure it wasn't something in my solution. I should have read the reviews because I wasn't the only one that happened to.

on a scale of white to purple, my solution has aqua ppm of ... ?

These test strips are completely unreliable. I use several different brands for our hot tub, and while every other strip clearly shows adequate chlorine levels, these consistently come back white, showing nothing at all. They simply don't work. Even if they did, I'm not sure why anyone would buy single-purpose strips when you can get multipurpose ones for around the same price. My regular test strips measure chlorine plus four or five other important levels in one go, which makes way more sense. Skip these and get a kit that actually does the job and gives you more information while you're at it.